A Synopsis of the North American Lagomorpha

BY

E. RAYMOND HALL

University of Kansas Publications

Museum of Natural History

Volume 5, No. 10, pp. 119-202, 68 figures in text

December 15, 1951

University of Kansas

LAWRENCE

1951

UNIVERSITY OF KANSAS PUBLICATIONS

The University of Kansas Publications, Museum of Natural History,
are offered in exchange for the publications of learned societies
and institutions, universities and libraries. For exchanges and information,
address the Exchange Desk, University of Kansas Library,
Lawrence, Kansas, U. S. A.

Museum of Natural History.—E. Raymond Hall, Chairman, Editorial Committee.

This series contains contributions from the Museum of Natural History.
Cited as Univ. Kans. Publ., Mus. Nat. Hist.

• Vol. 1. (Complete) Nos. 1-26. Pp. 1-638. August 15, 1946-January 20, 1951.
  


• Vol. 2. (Complete) Mammals of Washington. By Walter W. Dalquest. Pp.
  1-444, 140 figures in text. April 9, 1948.
  


• Vol. 3.
  
  
  
  1. The avifauna of Micronesia its origin, evolution, and
     distribution. By Rollin H. Baker. Pp. 1-359, 16 figures in text.
     June 12, 1951.
  
  
  2. A quantitative study of the nocturnal migration of birds.
     Pp. 361-472, 47 figures in text. June 29, 1951.
  
  
  3. Phylogeny of the waxwings and allied birds. By M. Dale Arvey.
     Pp. 473-530, 49 figures in text, 13 tables. October 10, 1951.
  
  
  4. Birds from the state of Veracruz, Mexico. By George H. Lowery,
     Jr., and Walter W. Dalquest. Pp. 531-649, 7 figures in text, 2
     tables. October 10, 1951.
  
  
  
  


• Vol. 4. In press.
  


• Vol. 5.
  
  
  
  1. Preliminary survey of a Paleocene faunule from the Angels Peak
     Area, New Mexico. By Robert W. Wilson. Pp. 1-11, 1 figure in
     text. February 24, 1951.
  
  
  2. Two new moles (genus Scalopus) from Mexico and Texas. By
     Rollin H. Baker. Pp. 17-24. February 28, 1951.
  
  
  3. Two new pocket gophers from Wyoming and Colorado. By E. Raymond
     Hall and H. Gordon Montague. Pp. 25-32. February 28,
     1951.
  
  
  4. Mammals obtained by Dr. Curt von Wedel from the barrier beach
     of Tamaulipas, Mexico. By E. Raymond Hall. Pp. 33-47, 1
     figure in text. October 1, 1951.
  
  
  5. Comments on the taxonomy and geographic distribution of some
     North American rabbits. By E. Raymond Hall and Keith R. Kelson.
     Pp. 49-58. October 1, 1951.
  
  
  6. Two new subspecies of Thomomys bottae from New Mexico and
     Colorado. By Keith R. Kelson. Pp. 59-71, one figure in text.
     October 1, 1951.
  
  
  7. A new subspecies of Microtus montanus from Montana and comments
     on Microtus canicaudus Miller. By E. Raymond Hall and
     Keith R. Kelson. Pp. 73-79. October 1, 1951.
  
  
  8. A new pocket gopher (genus Thomomys) from Eastern Colorado.
     By E. Raymond Hall. Pp. 81-85. October 1, 1951.
  
  
  9. Mammals taken along the Alaska highway. By Rollin H. Baker.
     Pp. 87-117, 1 figure in text. November 28, 1951.
  
  
  10. A synopsis of the North American Lagomorpha. By E. Raymond
      Hall. Pp. 110-202, 68 figures in text. December 15, 1951.
  
  
  
  

A Synopsis of the North American Lagomorpha

BY

E. RAYMOND HALL

University of Kansas Publications

Museum of Natural History

Volume 5, No. 10, pp. 119-202, 68 figures in text

December 15, 1951

University of Kansas

LAWRENCE

1951

University of Kansas Publications, Museum of Natural History

Editors: E. Raymond Hall, Chairman, A. Byron Leonard,
Edward H. Taylor, Robert W. Wilson

Volume 5, No. 10, pp. 119-202, 68 figures in text

December 15, 1951

University of Kansas

Lawrence, Kansas

PRINTED BY

FERD VOILAND, JR., STATE PRINTER

TOPEKA, KANSAS

1951

23-7988[Pg 121]

A Synopsis of the North American Lagomorpha

BY

E. RAYMOND HALL

The most popular small game mammal in nearly every part of
North America is one or another of the species of rabbits or hares.
The rabbit is one of the few species of wild game that still is hunted
commercially and sold for food on the open market. The close
association and repeated contact of man with these animals has resulted
in his contracting such of their diseases as are transmissible
to him. Consequently the rabbits and hares have figured in many
investigations concerned with public health and medicine. Because
the number of such investigations is increasing, there has been
an increasing number of specimens of these animals submitted to
mammalogists for identification; also, inquiries are received as to
the degree of relationship between two or more of the named kinds
of rabbits in which identical, or closely related, disease organisms
have been found; other inquiries have to do with the degree of
relationship of named kinds of rabbits and hares in widely separated
parts of the continent.

The monographs to which the investigator could turn to obtain
answers to some of these questions are Arthur H. Howell's "Revision
of the American Pikas" (1924), and Edward H. Nelson's "The
Rabbits of North America" (1909) published 27 and 42 years ago,
respectively. These monographs are still excellent sources of detailed
information, as, of course, also is Marcus Ward Lyon's "Classification
of the Hares and their Allies" (1904). The acquisition of
additional study specimens in recent years, however, has provided
new data on the geographic occurrence of several species, and study
of these specimens has given basis for a different arrangement of
several named kinds of the lagomorphs. Two principal aims of the
present synopsis, therefore, are to combine in one publication the
current taxonomic arrangement and as much as is known of the
geographic distribution of the several species and subspecies.

The maps herewith and listings of marginal localities are the
means chosen to present the information on geographic distribution.
The artificial key is supplemented by line drawings of skulls of certain
species and by a minimum of text to aid the user of the key.[Pg 122]
The skulls are necessary for the identification of some species of
the genus Sylvilagus. The skins, on the contrary, are essential for
the identification of the species of the genus Lepus in central Mexico
and in the Great Basin of the western United States. Consequently,
it has been impossible to construct a key based on external characters
only or on cranial features only. Furthermore, the only apparent
differences between a given pair of species in one region may
not be apparent in another region where the same two species occur
together. A case in point is provided by Sylvilagus floridanus and
Sylvilagus nuttallii where the Great Plains meet the eastern flank
of the Rocky Mountains and where the Sonoran desert meets the
southwestern flank of these mountains. The details are described by
Hall and Kelson (1951:52, 53) and are indicated in the part of the
accompanying artificial key that takes out the species Sylvilagus
nuttallii. Because of this geographic change in specific characters
and because of the slight amount of difference between certain
species of leporids, I have frequently resorted to geography, instead
of to morphology alone, in constructing the artificial key. Despite
this fault of the key to the lagomorphs, it, and the accompanying
account, I hope, will aid workers who need to identify kinds of
lagomorphs and to know about their geographic distribution.

Another reason for presenting a synopsis of the lagomorphs at this
time is that the presentation may bring suggestions for improvement
in the arrangement of the kind of information presented here; an account
along similar lines for all of the kinds of mammals native to
North America is in prospect. Corrections of, and additions to, the
material presented here will be welcomed and I shall be especially
grateful for suggestions as to a more useful arrangement of the data.

In arranging the families, genera and species the aim has been,
in each category, to list the most primitive members first and to
list last the one which presents the highest total of specialization.
The term total of specialization is used here, as Miller (1924:2)
used it, to denote the sum of the physical modifications which any
mammal, or taxonomic category of mammals, is supposed by the
author to have undergone during the course of its development
away from its original or generalized mammalian stock.

Subspecies of any one species are arranged alphabetically. On
the maps, of course, the subspecies are shown in their correct geographic
positions.

For each subspecies, or species if it has not been divided into
subspecies, there is given (1) the accepted scientific name (selected[Pg 123]
in accordance with the rules of the International Commission of
Zoological Nomenclature); (2) a citation to the account in which
the terminal part of the name was first proposed (the original description
of zoological parlance) followed by a statement of the
type locality; (3) a citation to the account in which the combination
of names (generic, specific and subspecific) used in the
present account first was employed unless the name combination
used here is the same as that in the original description; (4) synonyms
arranged in chronological order, and (5) marginal record
stations of occurrence.

These marginal records are arranged in clockwise order beginning
with the northernmost locality. If more than one of the marginal
localities lies on the line of latitude that is northernmost for
a given kind of mammal, the westernmost of these is recorded first.
The marginal localities that are represented by symbols on the corresponding
distribution map are in Roman type. Italic type is used
for those marginal localities that could not be represented by symbols
on the map because undue crowding, or overlapping, of the
symbols would have occurred. An understanding of how these
localities are arranged and knowledge as to which of these localities
are shown on the map will permit a person to associate any symbol
on a map with its corresponding place name.

Measurements are in millimeters unless otherwise indicated.
Capitalized color terms are after Ridgway (Color Standards and
Color Nomenclature, Washington, D. C., 1912), and uncapitalized
terms refer to no particular color standard. Several of the drawings
of skulls were reproduced originally in the "Mammals of Nevada"
(Hall, 1946) and I am grateful to the University of California Press
for permission to use them here. Those drawings were made by
Miss Viola Memmler. The other drawings are the work of Mrs.
Frieda Abernathy, Mrs. Diane (Danley) Sandidge, and Mrs. Virginia
(Cassel) Unruh. Initials on the drawings identify the individual's
work. The study here reported upon was aided by a contract
between the Office of Naval Research, Department of the
Navy, and the University of Kansas (NR 161-791). Also, assistance
with some of the field work was given by the Kansas University Endowment
Association and by Dr. Curt von Wedel. For the corrected
dates on several publications I am indebted to Dr. A. Remington
Kellogg. For assistance with the organization of the data for
the present account I am grateful to several persons, especially
to my wife, Mary F. Hall, and to Dr. Keith R. Kelson.[Pg 124]

Order LAGOMORPHA—Hares, Rabbits and Pikas

The order Lagomorpha is old in the geological sense; fossilized
bones and teeth of both pikas and rabbits are known from deposits of
Oligocene age and even at that early time the structural features distinguishing
these animals from other orders were well developed.

A noteworthy character of the order is the presence of four upper
incisor teeth (instead of only two as in the Rodentia); also, the
fibula is ankylosed to the tibia and articulates with the calcaneum.
Each of the first upper incisors has a longitudinal groove on its
anterior face.

All lagomorphs are herbivorous. They eat principally leaves
and non-woody stems although the bark of sprouts and bushes is
taken as second choice by rabbits and hares.

Correlation of structure and function is well illustrated among
the lagomorphs by the means which the different species employ
to detect and escape from their enemies. A gradient series is evident
in which the pikas and jack rabbits are the extremes. The
black-tailed jack rabbit, for example, in relation to size of the entire
animal, has the longest ears and longest hind legs. This kind of
lagomorph takes alarm when an enemy, for example, a coyote, is
yet a long way off. The jack rabbit seeks safety in running; even
when being overtaken by a pursuer that is close behind, the jack
rabbit still relies on its running ability instead of entering thick
brush or a hole in the ground where its larger-sized pursuer would
be unable to follow. A cottontail has shorter ears and shorter hind
legs. It allows the enemy to approach more closely than the jack
rabbit does before running, and then, although relying in some
measure on its running ability for escape, flees to a burrow or
thicket for safety from its pursuer. The brush rabbit with ears and
hind legs shorter than those of the cottontail seldom if ever ventures
farther than 45 feet away from the edge of dense cover. After an
enemy is near, the brush rabbit has merely to scamper back into
the brush. Still shorter of ear and hind leg is the pigmy rabbit
which ventures outside its burrow to feed only among the tall and
closely-spaced bushes of sagebrush among which its burrow is dug.
Detection of the slightest movement of an enemy on the opposite
side of the bush sends the pigmy rabbit, in one or a few jumps, into[Pg 125]
the mouth of its burrow and, if need be, below ground. The pika,
with the shortest ears and legs of all, lives in the rock slides and has
to do little more than drop off the top of a rock into a space between
the broken rocks when an enemy is detected near enough to
the pika to have a chance of seizing it.

The number of molts in a year, depending on the kind of lagomorph,
varies in adults from one (according to Nelson, 1909:31)
in the cottontails (genus Sylvilagus) to as many as three (according
to Lyman, 1943, and Severaid, 1945) in the varying hare (Lepus
americanus). Difficulties that I have experienced in attempting to
account for the variations in color and wear of the pelage of the
pika, Ochotona princeps, on the basis of two molts per year, make
me wonder if it, too, has three molts. Lepus townsendii certainly
has at least two molts per year.

Key to Families and Genera of Lagomorpha

• 
  1. Hind legs scarcely larger than forelegs; hind foot less than 40;
  nasals widest anteriorly; no supraorbital process on frontal; five
  cheek teeth on each side above
  


• 
  Family Ochotonidae, Genus Ochotona, p. 125
  


• 
  1´. Hind legs notably larger than forelegs; hind foot more than 40;
  nasals widest posteriorly; supraorbital process on frontal; six
  cheek teeth on each side above
  


• 
  Family Leporidae, p. 134
  


• 
  2. Interparietal fused with parietals (see fig. 49); hind foot
  usually more than 105
  


• 
  Genus Lepus, p. 170
  


• 
  2´. Interparietal not fused with parietals (see fig. 10); hind foot
  usually less than 105
  


• 
  Genera Romerolagus and Sylvilagus, pp. 137, 138
  

Family Ochotonidae—Pikas

Certain characters in which this family differs from the Leporidae (hares
and rabbits) are: hind legs scarcely longer than forelegs; ears short, approximately
as wide as high; no postorbital process on frontal; rostrum slender;
nasals widest anteriorly; maxilla not conspicuously fenestrated; jugal long and
projecting far posteriorly to zygomatic arm of squamosal; no pubic symphysis;
one less cheek-tooth above, the dental formula being i. 2/1, c. 0/0, p. 3/2, m. 2/3;
second upper maxillary tooth unlike third in form; last lower molar simple
(not double) or absent (in the extinct genus Oreolagus); cutting edge of
first upper incisor V-shaped; mental foramen situated under last lower molar.

Genus Ochotona Link—Pikas

Revised by A. H. Howell, N. Amer. Fauna, 47:1-57, August 21, 1924.

Characters.—Five teeth (excluding incisor) in lower jaw; first cheek-tooth
(p3) with more than one re-entrant angle; columns of lower molars angular[Pg 126]
internally; transverse width of any one column of a lower molariform tooth
more than double the width of the neck connecting it to the other column.

Subgenus PIKA Lacépède

Characters.—Skull flattened; interorbital region wide; maxillary orifice
roundly triangular; palatal foramina separate from anterior palatine foramina.

All of the living members of the family Ochotonidae belong to this genus.
American pikas all belong to the subgenus Pika, which occurs also in Eurasia.

The distribution is boreal and the animals live in talus. This broken rock
at the foot of a cliff provides interstices in which the animals live and store
grass and herbs. These plant materials are cut for food and stacked in piles
to dry in the sun, often beneath slabs of rock which protect the hay-piles
from rain. Pikas are diurnal, active throughout the year, and have a characteristic
call, "chickck-chickck." Young number two to five per litter.

Figs. 1-4. Ochotona princeps tutelata, Greenmonster Canyon, 8150 feet,
No. 38519 MVZ, , × 1.

Key to Nominal Species of Ochotona

• 
  1. North of 58° N latitude; underparts creamy white, without buffy
  wash; an indistinct grayish "collar" on shoulders


• 
  collaris, p. 126


• 
  1´. South of 58° N latitude; underparts washed with buff; no grayish
  "collar" on shoulders


• 
  princeps, p. 127

Ochotona collaris (Nelson)

Collared Pika

Ochotona princeps

Pika

Total length, 162-216; hind foot, 25-35; weight of O. p. tulelata, 6 121
(108-128), 2 121 and 129 grams. Upper parts varying from grayish to
Cinnamon-Buff depending on the subspecies; underparts with wash of buff.
Eight Nevadan females had an average of 3.1 (2-4) embryos. The mode
was 3.

Ochotona princeps albata Grinnell.

Ochotona princeps brooksi A. H. Howell.

Ochotona princeps brunnescens A. H. Howell.

[Pg 128]

Fig. 5. Distribution of Ochotona collaris and Ochotona princeps.

1. O. collaris


2. O. p. princeps


3. O. p. lutescens


4. O. p. septentrionalis


5. O. p. brooksi


6. O. p. cuppes


7. O. p. brunnescens


8. O. p. fenisex


9. O. p. fumosa


10. O. p. jewetti


11. O. p. taylori


12. O. p. schisticeps


13. O. p. muiri


14. O. p. albatus


15. O. p. sheltoni


16. O. p. tutelata


17. O. p. nevadensis


18. O. p. uinta


19. O. p. moorei


20. O. p. cinnamomea


21. O. p. fuscipes


22. O. p. utahensis


23. O. p. howelli


24. O. p. lemhi


25. O. p. goldmani


26. O. p. clamosa


27. O. p. ventorum


28. O. p. levis


29. O. p. figginsi


30. O. p. saxatilis


31. O. p. nigrescens


32. O. p. incana

[Pg 129]

Ochotona princeps cinnamomea J. A. Allen.

Ochotona princeps clamosa Hall and Bowlus.

Ochotona princeps cuppes Bangs.

Ochotona princeps fenisex Osgood.

Ochotona princeps figginsi J. A. Allen.

[Pg 130]

Ochotona princeps fumosa A. H. Howell.

Ochotona princeps fuscipes A. H. Howell.

Ochotona princeps goldmani A. H. Howell.

Ochotona princeps howelli Borell.

Ochotona princeps incana A. H. Howell.

Ochotona princeps jewetti A. H. Howell.

[Pg 131]

Ochotona princeps lemhi A. H. Howell.

Ochotona princeps levis Hollister.

Ochotona princeps lutescens A. H. Howell.

Ochotona princeps moorei Gardner.

Ochotona princeps muiri Grinnell and Storer.

Ochotona princeps nevadensis A. H. Howell.

[Pg 132]

Ochotona princeps nigrescens V. Bailey.

Ochotona princeps princeps (Richardson).

Ochotona princeps saxatilis Bangs.

Ochotona princeps schisticeps (Merriam).

Ochotona princeps septentrionalis Cowan and Racey.

Ochotona princeps sheltoni Grinnell.

Ochotona princeps taylori Grinnell.

Ochotona princeps tutelata Hall.

Ochotona princeps uinta Hollister.

Ochotona princeps utahensis Hall and Hayward.

Ochotona princeps ventorum A. H. Howell.

[Pg 134]

Family Leporidae—Rabbits and Hares

Hind legs longer than forelegs; ears longer than wide; frontal bone
carrying supraorbital process consisting always of posterior arm and
sometimes of anterior arm; rostrum wide; nasals not wider anteriorly
than posteriorly; maxillae conspicuously fenestrated; jugal
projecting less than half way from zygomatic root of squamosal to
external auditory meatus (except in Romerolagus); pubic symphysis
well marked; dental formula, i. 2/1, c. 0/0, p. 3/2, m. 3/3 (but m. 2/3 in Pentalagus
of Liu Kiu Islands south of Japan); second upper maxillary
tooth like third in form; last lower molar double; cutting edge
of first upper incisor straight; mental foramen of mandible situated
under first lower cheek-tooth. Females average larger than males
in all members of this family. (See Orr, 1940:20.) The reverse is
true in most other families of mammals.

Hare is a name applied to any lagomorph whose young are born
fully haired, with the eyes open, and able to run about a few minutes
after birth. The young are born in the open, not in a nest.
All of the species of the genus Lepus are hares. The species of
leporids of all genera other than Lepus, in North America at least,
are rabbits. Their young are born naked, blind, and helpless, in a
nest especially built for them and lined with fur. Considering the
degree of development of the young at birth, the gestation periods
are about what a person would expect: 26 to 30 days in Sylvilagus
and 36 to 47 days in Lepus (see Severaid, 1950:356-357). Vernacular
names are misleading because the names jack rabbit and snowshoe
rabbit are applied to hares; also, Belgian hare is a name applied
to a rabbit (genus Oryctolagus) that is commonly bred in captivity.
There are many domestic strains and varieties of Oryctolagus and
the animals are second only to poultry in some areas as a protein
food for man. Also, the pelts are sold as a source of felt and many
of the skins are dyed and processed for making fur coats and other
fur-pieces that appear on the market under names not readily associated
with rabbit.

Rabbits and hares are crepuscular and possibly more nocturnal
than diurnal. So far as I know they do not store food as do their
diurnal relatives, the pikas. Some leporids, however, have an unusual,
and possibly unique, method of processing food: Two types
of vegetable pellets are expelled from the anal opening of the
digestive tract; the dark brownish pellets, from which the nutriments[Pg 135]
have been extracted, are feces, but the greenish pellets seem
to be only slightly predigested foods which are re-eaten. Southern
(1942:553), among others, has written about this. This system
functionally resembles that in the ruminants where a cud of vegetation
is returned to the mouth, from one part of the stomach, to be
re-chewed and finally swallowed.

Because the causative organism of a disease that decimates dense
populations of small mammals, and some other kinds of vertebrates,
was isolated first in leporids, this disease, tularemia, is more associated
in the popular mind with rabbits than with other kinds of
mammals. Actually, many kinds of mammals are quite as likely
to have tularemia as are rabbits. Now that streptomycin is available,
cases of tularemia in persons are easily cured.

Key to Species of the Genera Sylvilagus and Romerolagus

• 
  1. Antorbital extension of supraorbital process more than 1/2 length of
  posterior extension; first upper cheek-tooth with only one
  re-entrant angle on anterior face; re-entrant angle of second upper
  cheek-tooth not crenate
• Sylvilagus idahoensis, p. 139


• 
  1´. Antorbital extension of supraorbital process less than 1/2 of
  posterior extension or entirely absent; first upper cheek-tooth with
  more than one (usually 3) re-entrant angles on anterior face;
  re-entrant angle of second upper cheek-tooth crenate.


• 
  2. Anterior extension of supraorbital process absent (or if a point is
  barely indicated, then 5/6 or all of posterior process fused to
  braincase).


• 
  3. Tympanic bulla smaller than foramen magnum; hind foot more than
  74; geographic range wholly in United States.


• 
  4. Ear more than 58 from notch in dried skin; basilar length of
  skull more than 63
• Sylvilagus aquaticus, p. 166


• 
  4´. Ear less than 58 from notch in dried skin; basilar length of
  skull less than 63.


• 
  5. Underside of tail white; posterior extension of supraorbital
  process tapering to a slender point, this point free of
  braincase or barely touching it and leaving a slit or long
  foramen
• Sylvilagus transitionalis, p. 160


• 
  5´. Underside of tail brown or gray; posterior extension of
  supraorbital process always fused to skull, usually for
  entire length but in occasional specimens there is small
  foramen at middle of posterior extension of supraorbital
  process
• Sylvilagus palustris, p. 147


• 
  3´. Tympanic bulla as large as foramen magnum; hind foot less than
  74; geographic range limited to southern edge of Mexican
  tableland at high elevations
• Romerolagus diazi, p. 138


• 
  2´. Anterior extension of supraorbital process present, and posterior
  extension free of braincase or leaving a slit between the process
  and braincase.


• 
  6. Tympanic bullae large (see fig. 26).


• Sylvilagus audubonii, p. 162


• 
  6´. Tympanic bullae small (see figs. 23, 25 and 27).


• 
  7. Restricted to Pacific coastal strip from Columbia River
  south to tip of Baja California, west of Sierra
  Nevada-Cascade Mountain Chain; hind foot less than 81.


• Sylvilagus bachmani and S. mansuetus, pp. 143, 147


• 
  7´. East of the Pacific coastal strip mentioned in 7; hind
  foot usually more than 81.


• 
  8. If north of United States-Mexican boundary:


• 
  9. In Arizona, New Mexico and southern Colorado
  posterior extension of supraorbital process free of
  braincase, and supraoccipital shield posteriorly
  pointed; from central Colorado north into Canada
  diameter of external auditory meatus more than crown
  length of last three cheek-teeth


• Sylvilagus nuttallii, p. 161


• 
  9´. In Arizona, New Mexico and southeastern Colorado
  posterior extension of supraorbital process of
  frontal with its tip against, or fused to,
  braincase, and supraoccipital shield posteriorly
  truncate or notched; from central Colorado north
  into Canada, diameter of external auditory meatus
  less than crown length of last three cheek-teeth


• Sylvilagus floridanus, p. 154


• 
  8´. If south of United States-Mexican boundary:


• 
  10. Geographic range restricted to Tres Marias Islands


• Sylvilagus graysoni, p. 169


• 
  10´. Geographic range not including Tres Marias
  Islands.


• 
  11. Underside of tail dingy gray or buffy (not
  white).


• 
  12. Tail short (less than 30) and brown like rump;
  ear from notch (dry) less than 53;
  interorbital breadth less than 16.


• Sylvilagus brasiliensis, p. 141


• 
  12´. Tail of moderate length (more than 30) and
  dingy gray; ear from notch (dry) more than
  53; interorbital breadth more than 16


• Sylvilagus insonus, p. 168


• 
  11´. Underside of tail distinctly white.


• 
  13. Total length more than 476; ear from notch
  (dry) more than 64; interorbital breadth
  usually more than 19.3; geographic range,
  southwestern Mexico north of the Isthmus of
  Tehuantepec.
• Sylvilagus cunicularius, p. 169


• 
  13´. Total length less than 476; ear from notch
  (dry) less than 64; interorbital breadth
  usually less than 19.3; geographic range,
  Canada to Panamá


• Sylvilagus floridanus, p. 154

[Pg 137]

Genus Romerolagus Merriam—Volcano Rabbit

Total length 300 to 311; tail rudimentary; hind foot, 52; ear from notch
(dry), 36; upper parts grizzled buffy brown or dull cinnamon brown; underparts
dingy gray; anterior projection of supraorbital process absent; jugal projecting
posteriorly past squamosal root of zygomatic arch more than half way
to external auditory meatus. The two cranial characters mentioned are resemblances
to pikas although the skull otherwise resembles that of the true
rabbits. The genus contains only the one living species.

Living in well defined runways in the dense sacoton grass, these small
rabbits are mainly nocturnal and crepuscular, but sometimes are active by day,
especially in cloudy weather in the period of mating.

Fig. 6. Distribution of Romerolagus diazi.

[Pg 138]

Romerolagus diazi (Diaz)

Volcano Rabbit

Genus Sylvilagus Gray—Cottontails and Allies

Total length, 291-538; tail, 18-73; hind foot, 71-110; ear from notch
(dry) 41-74. Grayish to dark brownish above and lighter below;
sutures of interparietal bone distinct throughout life; second to
fourth cervical vertebrae broader than long with dorsal surface
flattened and without carination.

The delectable flesh of members of this genus, the large numbers
that occur on a small area, even in thickly settled rural areas, and the
wariness that rabbits soon develop when much hunted, give them
top ranking among small game mammals. Tens of thousands of
cottontails in Kansas and Missouri (Sylvilagus floridanus and some
S. audubonii) are captured alive, transported to the eastern United
States and released there to bolster the local supply of game. Considering
that certain ectoparasites are limited to certain hosts and
that some ectoparasites transmit such diseases as Rocky Mountain
Spotted Fever whereas other ectoparasites do not, this transplantation
of rabbits is dangerous. Also, expenditure of $100.00 on improving
the habitat for Sylvilagus in a given area in the eastern
United States would produce more cottontails than the expenditure
of the same sum for live animals, from the Middlewest, that are to
be released (see Langenbach and Beule, 1942:14, 15 and 30).

Different species venture different distances from cover to feed.
The Audubon cottontail of west-central California ventures a hundred
feet and more from cover but the brush rabbit was never seen[Pg 139]
(Orr, 1940:182) farther than 42 feet from cover. In the thirties,
when a gladiolus farmer from the chaparral belt of Santa Clara
County, California, visited the University of California seeking advice
on how to prevent damage by "cottontails" to his gladioli
plantings, we asked the farmer if brush rabbits or cottontails were
responsible and suggested to the farmer, who was unable to distinguish
between the two, that an animal be killed and submitted
for identification. When this was done, the brush rabbit (Sylvilagus
bachmani) was found to be responsible for the damage. Robert
T. Orr's recommendation that the chaparral (brush) be cut back
45 feet from the gladioli plantings was reluctantly followed and
proved to be effective. A letter from a Santa Clara County agricultural
official a couple of years later expressed thanks for the recommendation
made by Orr, and estimated that adoption of his recommendations
saved farmers of that one county $40,000 annually.
This incident illustrates how detailed knowledge of the life history
of a given kind of animal and control of its environment, rather than
direct "control" of the animal, is sometimes of value to man.

The genus Sylvilagus is restricted to the New World; the two
species Sylvilagus brasiliensis and S. floridanus are the only two
which occur in South America and they occur also in North America.

Subgenus BRACHYLAGUS Miller—Pigmy Rabbit

Sylvilagus idahoensis (Merriam)

Pigmy Rabbit

Fig. 7. Distribution of Sylvilagus idahoensis.

[Pg 141]

Subgenus SYLVILAGUS Gray—Cottontails and Allies

Characters of subgeneric worth, in contrast to those of the subgenus
Brachylagus, are: First premolar, in upper jaw and in lower
jaw, with more than one fold in the enamel; infolded enamel, which
divides each molar tooth into two parts, crenate.

The many nominal species of the subgenus Sylvilagus belong
to no more than 12 and perhaps to only ten full species. The now
more abundant specimens than were available a half century ago
reveal also that there are less trenchant differences between some of
the species than were supposed to exist when the five names for
genera or subgenera listed immediately above were proposed.
Some species can be placed in each of two subgenera with almost
equal propriety. If used, four of the five subgeneric names mentioned
above would contain only one species each. It seems that
no useful purpose is served by attempting to fit the several species
of the genus Sylvilagus into more than the two subgenera Brachylagus
and Sylvilagus; the other names, Tapeti Gray, Microlagus
Trouessart, Limnolagus Mearns, and Paludilagus Hershkovitz, are
here arranged as synonyms of the subgeneric name Sylvilagus Gray.

Sylvilagus brasiliensis

Forest Rabbit

Total length, 380-420; tail, 20-21; hind foot, 77-80; ear from notch
(dry), 39-46. The principal characters of this species are small size,
dark color, short tail, and dingy buffy (not white) undersurface of
the tail. These rabbits rest in forests or other thick vegetative cover
and do not venture far from such cover to feed.

Sylvilagus brasiliensis consobrinus Anthony.

Sylvilagus brasiliensis dicei Harris.

Fig. 8. Distribution of Sylvilagus brasiliensis.

1. S. b. truei


2. S. b. gabbi


3. S. b. dicei


4. S. b. consobrinus


5. S. b. messorius


6. S. b. incitatus

Sylvilagus brasiliensis gabbi (J. A. Allen).

[Pg 143]

Sylvilagus brasiliensis incitatus (Bangs).

Sylvilagus brasiliensis messorius Goldman.

Sylvilagus brasiliensis truei (J. A. Allen).

Sylvilagus bachmani

Brush Rabbit

Fig. 9. Distribution of Sylvilagus bachmani
and Sylvilagus mansuetus.

1. S. b. ubericolor


2. S. b. tehamae


3. S. b. macrorhinus


4. S. b. riparius


5. S. b. mariposae


6. S. b. bachmani


7. S. b. virgulti


8. S. b. cinerascens


9. S. b. rosaphagus


10. S. b. howelli


11. S. b. exiguus


12. S. b. peninsularis


13. S. b. cerrosensis


14. S. mansuetus

Size small. Total length, 300-375; tail, 20-43; hind foot, 64-81;
ear from notch (dry), 50-64; weight (topotypes of S. b. macrorhinus)
16 679 (561-832), 22 707 (517-843) grams. Body
uniformly dark brown or brownish gray, but tail whitish beneath;
hair on midventral part of body gray at base; only a slight crenulation
of ridge of enamel which separates an individual molariform
tooth into anterior and posterior sections. From Sylvilagus audubonii,
the only other species of Sylvilagus in the same geographic
area, S. bachmani differs in smaller size, less white on underparts
(the hairs on the midventral part of the body being gray instead of
white at base), shorter ears and legs, and a less crenulated ridge of
enamel separating the anterior and posterior parts of a molariform
tooth.

The brush rabbit is a Pacific Coastal species; as may be seen from
figure 9 on the next page, this species occurs from the Columbia
River on the north to the tip of Baja California on the south. Nowhere,
so far as I can learn, does it occur as far east as the crest
of the Cascade-Sierra Nevada Mountain Chain. Throughout its
range the brush rabbit is closely associated with—in fact, lives in—the
chaparral that is dense enough to afford protection from
raptorial birds and the larger carnivorous mammals. The rabbit's[Pg 144]
reliance on protective cover is
so great that, as pointed out on
an earlier page, a person can
turn this trait to advantage in
protecting cultivated crops
from inroads that the rabbits
might make on them. The protection
is afforded by clearing
the brush from a strip forty-five
feet wide so that the cleared
strip intervenes between the
cultivated crops and the brushy
shelter. The rabbits will not
risk crossing the open strip and
hence do not reach the growing
crops.

Brush rabbits use simple
"forms" in the brush for resting.
Only one observer (Orr, 1940:
173) has reported an individual
entering a hole. In patches of
chaparral in which the rabbits
live they make runways that
are especially well defined
at the edges of the brush. The
outer entrance to a runway is
tunnellike and one to two feet
from the outer entrance there
is a special form that serves as
a lookout post. A brush rabbit
that is about to venture into the
open ordinarily pauses in such
a form for several minutes, presumably
to satisfy itself that no
enemy is in the open area
whither the rabbit is bound.

The breeding season is from
January to June, at least in
California. There are 2 to 5
young, averaging 3.5 per litter.
They are born in a nest.[Pg 145]

Sylvilagus bachmani bachmani (Waterhouse).

Sylvilagus bachmani cerrosensis (J. A. Allen).

Sylvilagus bachmani cinerascens (J. A. Allen).

Sylvilagus bachmani exiguus Nelson.

Sylvilagus bachmani howelli Huey.

Sylvilagus bachmani macrorhinus Orr.

Sylvilagus bachmani mariposae Grinnell and Storer.

[Pg 146]

Sylvilagus bachmani peninsularis (J. A. Allen).

Sylvilagus bachmani riparius Orr.

Sylvilagus bachmani rosaphagus Huey.

Sylvilagus bachmani tehamae Orr.

Sylvilagus bachmani ubericolor (Miller).

Sylvilagus bachmani virgulti Dice.

[Pg 147]

Sylvilagus mansuetus

Brush Rabbit

This insular species is closely related to Sylvilagus bachmani and
is distinguished by paleness, proportionately longer and narrower
skull, fusion to skull of anterior arm of supraorbital process, and
larger jugal.

Sylvilagus palustris

Marsh Rabbit

(See figure 42)

Total length, 425-440; tail, 33-39; hind foot, 88-91; ear from notch
(dry), 45-52. Upper parts blackish brown or reddish brown; underside
of tail brownish or dingy gray (not white); ears, tail and hind
feet short; posterior and anterior extensions of supraorbital processes
joined to skull along most (or all) of their extent. The lack
of white on the underside of the tail is a ready means of distinguishing
this species from the other species of the genus which occur
within its geographic range. The species occurs in the lowlands,
possibly not above 500 feet altitude, of the Lower Austral and
Tropical life-zones. In Florida, Blair (1936) found that the marsh
rabbit ate 29 per cent of its bodily weight in green food each day
and that the number of embryos in 3 females was 4, 4 and 3.

Sylvilagus palustris paludicola (Miller and Bangs).

Sylvilagus palustris palustris (Bachman).

[Pg 148]

Figs. 10-14. Dorsal views of skulls of rabbits. All × 1.

• Fig. 10. Romerolagus diazi, 31 km. S Mexico City, D. F. No.
  30815 KU, .


• Fig. 11. Sylvilagus idahoensis, Millett P. O., Nevada. No.
  37275 MVZ, .


• Fig. 12. Sylvilagus brasiliensis truei, 30 km. SSE Jesus Carranza,
  Veracruz. No. 32128 KU, .


• Fig. 13. Sylvilagus bachmani macrorhinus, 1700 feet, Alpine
  Creek Ranch, San Mateo County, California. No. 53382 MVZ, .


• Fig. 14. Sylvilagus palustris palustris, Riceboro, Georgia. No.
  45502 USNM, . (After Nelson, 1909: pl. 12, fig. 3.)

[Pg 149]

Figs. 15-19. Dorsal views of skulls of rabbits. All × 1.

• Fig. 15. Sylvilagus nuttallii grangeri, 1/2 mi. E. Jefferson, Nev. No. 58527, .


• Fig. 16. Sylvilagus audubonii minor, 3290 ft., Neville Spring, Grapevine
  Mts., Big Bend, Brewster Co., Texas. No. 80519 MVZ, .


• Fig. 17. Sylvilagus floridanus mearnsi, 4 mi. NE Lawrence, Douglas Co.,
  Kansas. No. 3774 KU, .


• Fig. 18. Sylvilagus a. aquaticus, Crawford Co., Kansas. No. 8544 KU. .


• Fig. 19. Sylvilagus cunicularius cunicularius, 3 km. W Acultzingo, Veracruz.
  No. 30749 KU, .

[Pg 150]

Figs. 20-24. Ventral views of skulls of rabbits. All × 1. Different views of
the first four of these skulls are shown in figs. 10-13.

• Fig. 20. Romerolagus diazi.


• Fig. 21. Sylvilagus idahoensis.


• Fig. 22. Sylvilagus brasiliensis truei.


• Fig. 23. Sylvilagus bachmani macrorhinus.


• Fig. 24. Sylvilagus palustris palustris, Society Hill, South Carolina. No. 2089
  USNM (after Lyon, 1904: pl. 76, fig. 6).

[Pg 151]

Figs. 25-29. Ventral views of skulls of rabbits. All × 1. Different views
of these skulls are shown in figs. 15-19.

• Fig. 25. Sylvilagus nuttallii grangeri.


• Fig. 26. Sylvilagus audubonii minor.


• Fig. 27. Sylvilagus floridanus mearnsi.


• Fig. 28. Sylvilagus aquaticus aquaticus.


• Fig. 29. Sylvilagus cunicularius cunicularius.

[Pg 152]

Figs. 30-34. Lateral views of skulls of rabbits. All × 1.
Different views of these skulls are shown in figs. 10-15.

• Fig. 30. Romerolagus diazi.


• Fig. 31. Sylvilagus idahoensis.


• Fig. 32. Sylvilagus brasiliensis truei.


• Fig. 33. Sylvilagus bachmani macrorhinus.


• Fig. 34. Sylvilagus nuttallii grangeri.

[Pg 153]

Figs. 35-38. Lateral views of skulls of rabbits. All × 1.
Different views of these skulls are shown in figs. 16-19.

• Fig. 35. Sylvilagus audubonii minor.


• Fig. 36. Sylvilagus floridanus mearnsi.


• Fig. 37. Sylvilagus aquaticus aquaticus.


• Fig. 38. Sylvilagus cunicularius cunicularius.

[Pg 154]

Sylvilagus floridanus

Florida Cottontail

Total length, 375-463; tail, 39-65; hind foot, 87-104; ear from
notch (dry), 49-68; upper parts brownish or grayish; underside
of tail white; skull with transversely thick posterior extension of
supraorbital process of frontal. The geographic range is the largest
of all of the North American species of the genus Sylvilagus;
from Canada the species occurs south at least to Costa Rica and
it may occur in Panamá for the species is recorded also from South
America.

In the western part of the Great Plains this species is confined to
the riparian growth along streams and Sylvilagus audubonii occupies
the remainder of the terrain. In New Mexico and southwestern
Texas S. floridanus is confined to the boreal life-zones where
timber provides denser cover than is found in the lower life-zones.
The zonal range is from the Canadian Life-zone into the Tropical
Life-zone. It is not surprising, therefore, that there is much geographic
variation in the shape and size of the skull. There is so
much geographic variation in the skull that it is impossible, at this
writing at least, to frame a description that will enable the reader
to distinguish the skull from those of all other species of the genus.
In any given area, however, it is possible, easily and certainly, to
distinguish the skulls of S. floridanus from those of the other species
which occur in that area.

Sylvilagus floridanus alacer (Bangs).

Sylvilagus floridanus ammophilus A. H. Howell.

[Pg 155]

Fig. 39. Distribution of Sylvilagus nuttallii, S. floridanus and S. insonus.

Sylvilagus floridanus aztecus (J. A. Allen).

[Pg 156]

Sylvilagus floridanus chapmani (J. A. Allen).

Sylvilagus floridanus chiapensis (Nelson).

Sylvilagus floridanus cognatus Nelson.

Sylvilagus floridanus connectens (Nelson).

Sylvilagus floridanus costaricensis Harris.

[Pg 157]

Sylvilagus floridanus floridanus (J. A. Allen).

Sylvilagus floridanus hitchensi Mearns.

Sylvilagus floridanus holzneri (Mearns).

Sylvilagus floridanus hondurensis Goldman.

Sylvilagus floridanus llanensis Blair.

[Pg 158]

Sylvilagus floridanus mallurus (Thomas).

Sylvilagus floridanus mearnsii (J. A. Allen).

Sylvilagus floridanus orizabae (Merriam).

Sylvilagus floridanus restrictus Nelson.

[Pg 159]

Sylvilagus floridanus robustus (V. Bailey).

Sylvilagus floridanus russatus (J. A. Allen).

Sylvilagus floridanus similis Nelson.

Sylvilagus floridanus subcinctus (Miller).

Sylvilagus floridanus yucatanicus (Miller).

[Pg 160]

Sylvilagus transitionalis (Bangs)

New England Cottontail

Fig. 40. Distribution of Sylvilagus transitionalis.

[Pg 161]

Total length, 388; tail, 39; hind foot, 95; ear from notch (dry),
52. Upper parts almost pinkish buff, varying to almost ochraceous
buff; back overlaid by a distinct black wash giving a penciled effect;
anterior extension of supraorbital process obsolete or short and
closely appressed to orbital rim; tympanic bullae small, smaller than
in any subspecies of S. floridanus in the United States. S. transitionalis
is a forest-inhabiting species—more so than is S. floridanus.

Sylvilagus nuttallii

Nuttall Cottontail

(See figure 39)

Total length, 350-390; tail, 44-50; hind foot, 88-100; ear from
notch (dry), 55-56; weight in Nevada, 678, 3 928 (868-1032)
grams. Hind feet densely covered with long hair; ear short; tympanic
bulla of moderate size. In the northern part of its range
S. nuttallii occurs principally in the sagebrush areas but it occurs
also in the timbered areas of the Transition Life-zone and almost exclusively
in timbered areas in the southern part of its range. From
S. floridanus, S. nuttallii along the eastern margin of its range differs
in more slender rostrum, and larger external auditory meatus. In
New Mexico and Arizona, S. nuttallii differs from S. floridanus in
the posteriorly pointed and un-notched supraoccipital shield and
in the posterior extension of the supraorbital process, the tip of
which projects free from the braincase or merely lies against the
braincase instead of being firmly welded to the side of the skull.
From S. audubonii, S. nuttallii differs in shorter ears, smaller tympanic
bullae and smaller hind legs; S. nuttallii usually occurs at
higher elevations, or where the two occur at approximately the
same elevation S. nuttallii occurs in wooded or brushy areas and
S. audubonii lives on the plains or in relatively open country. Eight
females contained an average of 6.1 (4-8) embryos.

Sylvilagus nuttallii grangeri (J. A. Allen).

Sylvilagus nuttallii nuttallii (Bachman).

Sylvilagus nuttallii pinetis (J. A. Allen).

Sylvilagus audubonii

Audubon Cottontail

Total length, 350-420; tail, 45-75; hind foot, 75-100; ear from notch
(dry), 55-70; weight of S. a. vallicola, 7 912 (835-988), 2 1096,
1191 grams. Long hind legs, long ears, sparseness of hair on the ears,
shortness of hair on the feet, prominent (upturned) supraorbital
process of the skull and much inflated tympanic bullae are characters
of this wide-spread species. Embryos in 19 Californian females
averaged 3.6 (2-6) per female.[Pg 163]

Fig. 41. Distribution of Sylvilagus audubonii.

[Pg 164]

Sylvilagus audubonii arizonae (J. A. Allen).

Sylvilagus audubonii audubonii (Baird).

Sylvilagus audubonii baileyi (Merriam).

Sylvilagus audubonii cedrophilus Nelson.

[Pg 165]

Sylvilagus audubonii confinis (J. A. Allen).

Sylvilagus audubonii goldmani (Nelson).

Sylvilagus audubonii minor (Mearns).

Sylvilagus audubonii neomexicanus Nelson.

Sylvilagus audubonii parvulus (J. A. Allen).

[Pg 166]

Sylvilagus audubonii sanctidiegi (Miller).

Sylvilagus audubonii vallicola Nelson.

Sylvilagus audubonii warreni Nelson.

Sylvilagus aquaticus

Swamp Rabbit

Total length, 530-540; tail, 67-71; hind foot, 105-110; length of
ear from notch (dry), 63-67. Upper parts blackish brown or reddish
brown; underparts with some white; under side of tail white;
skull robust; posterior extensions of supraorbital processes joined
for their entire length with side of braincase or, in some specimens,
with a small foramen between the braincase and the base of the
posterior extension of the supraorbital process. This big rabbit is
a stronger runner than the smaller marsh rabbit and is easily distinguished
from the smaller species by larger size and white, instead
of brownish or grayish, underside of the tail.

Sylvilagus aquaticus aquaticus (Bachman).

[Pg 167]

Fig. 42. Distribution of Sylvilagus palustris and Sylvilagus aquaticus.

1. S. p. palustris


2. S. p. paludicola


3. S. a. aquaticus


4. S. a. littoralis

Sylvilagus aquaticus littoralis Nelson.

Sylvilagus insonus (Nelson)

Omilteme Cottontail

(See figure 39)

Total length, 435; tail, 42.5; hind foot, 95; ear from notch (dry),
61. Color grayish brown above and dingy (not white) below; tail
dingy buffy below and dull rusty brown above. The collectors
thought that the species was restricted to the forested parts of the
Sierra Madre del Sur between 7000 and 10,000 feet altitude in the
Mexican state of Guerrero.

Fig. 43. Distribution of Sylvilagus cunicularius and Sylvilagus graysoni.

1. Sylvilagus cunicularius insolitas


2. Sylvilagus cunicularius pacificus


3. Sylvilagus cunicularius cunicularius


4. Sylvilagus graysoni

[Pg 169]

Sylvilagus cunicularius

Mexican Cottontail

Total length, 485-515; tail, 54-68; hind foot, 108-111; ear from
notch (dry), 60-63. Pelage coarse; upper parts brownish gray;
skull massive; posterior extensions of supraorbital processes varying
from those that project free to those that have the tips, or tips and a
considerable part of the processes, attached to the braincase.

Sylvilagus cunicularius cunicularius (Waterhouse).

Sylvilagus cunicularius insolitus (J. A. Allen).

Sylvilagus cunicularius pacificus (Nelson).

Sylvilagus graysoni (J. A. Allen)

Tres Marias Cottontail

Total length, 480; tail, 51; hind foot, 99; ear from notch (dry),
57. This insular species is closely related to Sylvilagus cunicularius
of the adjacent mainland but has notably shorter ears and more reddish
on the upper parts, sides and legs; the skull is slenderer, es[Pg 170]pecially
in the rostral region. The posterior extensions of the supraorbital
process are united to the braincase throughout most of their
length as in Sylvilagus palustris. The species seems to have a
narrow vertical range, occurring from sea level up to only 200 feet.

Genus Lepus Linnaeus—Hares and Jack Rabbits

Total length, 363-664; tail, 25-112; hind foot, 112-189; ear from
notch (dry), 62-144. Upper parts grayish, brownish or black; interparietal
bone fused to surrounding bones; cervical vertabrae long,
2nd and 3rd being longer than wide; transverse processes of lumbar
vertabrae long, the longest one equal to the length of the centrum
to which it is attached plus half of the length of the preceding
centrum; free extremity of transverse process of lumbar vertebra
considerably expanded; distance from anterior edge of acetabulum
to extreme anterior point of ilium less than distance from former
point to most distant point of ischium; ulna reduced in size along
middle part of shaft, and, excepting the lower extremity, placed
almost entirely behind radius.

All members of the genus Lepus are technically hares, as these
are defined in the account of the family Leporidae. The largest
members of the order Lagomorpha are members of the genus
Lepus. No domestic strains have been developed but effort in this
direction might be profitable, in as much as the so-called Belgian
hares of the related genus, Oryctolagus, have done well in captivity.

In the past it has been customary to recognize two or more subgenera
of the genus Lepus. The species are a less diverse lot than[Pg 171]
those in some other genera, however, and it seems that no useful
purpose is served by recognizing subgenera. Accordingly, the
several names proposed for this purpose are arranged here as
synonyms of the generic name Lepus Linnaeus.

The introduction of the European Hare (Lepus europaeus) into
the eastern part of the North American Continent has been successful
in the sense that the animal is multiplying. If it continues
to increase, the increase almost certainly will be at the expense of
some native species of rabbit. This circumstance and the unfortunate
consequences of the introduction of the European rabbit
(Oryctolagus cuniculus) in New Zealand (see Wodzicki, 1950:107-141)
and Australia (see Stead, 1925:355-358) give basis for effort
to exterminate the alien species before it spreads more widely.

Key to the Species of the Genus Lepus

• 
  1. North of 34° N latitude.


• 
  2. All white pelage (tips of ears sometimes black).


• 
  3. North of line from Port Simpson, British Columbia, to Halifax,
  Nova Scotia.


• 
  4. Basilar length of skull more than 67; ear from notch usually
  more than 73 dry (77 fresh); first upper incisors inscribing
  an arch of a circle the radius of which is more than 9.6 mm.


• 
  5. Geographic range east of Mackenzie River.


• 
  Lepus arcticus, p. 178


• 
  5´. Geographic range west of Mackenzie River.


• Lepus othus, p. 177


• 
  4´. Basilar length of skull less than 67; ear from notch usually
  less than 73 dry (77 fresh); first upper incisors inscribing
  an arch of a circle the radius of which is less than 9.6 mm.


• 
  Lepus americanus, p. 173


• 
  3´. South of a line from Port Simpson, British Columbia to Halifax,
  Nova Scotia.


• 
  5. Ear from notch more than 82 dry (87 fresh); least
  interorbital breadth more than 26


• 
  Lepus townsendii, p. 180


• 
  5´. Ear from notch less than 82 dry (87 fresh); least
  interorbital breadth less than 26


• 
  Lepus americanus, p. 173


• 
  2´. Brownish or grayish pelage.


• 
  6. Tail blackish or brownish all around (in specimens not
  having completed molt on tail, white winter pelage may be
  present); basilar length less than 67 mm.


• 
  Lepus americanus, p. 173


• 
  6´. Tail partly or wholly white.


• 
  7. Tail black on upper surface.


• 
  8. Upper sides of hind feet without a trace of white;
  upper parts tawny.


• 
  Lepus europaeus, p. 189


• 
  8´. Upper sides of hind feet with more or less white or
  whitish; upper parts grayish or brownish


• 
  [Pg 172]Lepus californicus, p. 181


• 
  7´. Tail all white or (in some Lepus townsendii) with
  faint buffy or dusky median line on top but this line
  not extending on to rump (as in L. californicus).


• 
  9. Geographic range north of a line from Port Simpson,
  British Columbia, to Halifax, Nova Scotia.


• 
  10. Geographic range east of Mackenzie River


• 
  Lepus arcticus, p. 178


• 
  10´. Geographic range west of Mackenzie River


• 
  Lepus othus, p. 177


• 
  9´. Geographic range south of a line from Port Simpson,
  British Columbia, to Halifax, Nova Scotia


• 
  Lepus townsendii, p. 180


• 
  1´. South of 34° N latitude.


• 
  11. In state of Tamaulipas, México.


• 
  Lepus californicus, p. 181


• 
  11´. Range outside Tamaulipas, México.


• 
  12. Ears with terminal black patch (on outside).


• 
  Lepus californicus and Lepus insularis,
  pp. 181, 186


• 
  12´. Ears without terminal black patch.


• 
  13. Ear from notch, dry more than 130 (137
  fresh),


• 
  Lepus alleni, p. 188


• 
  13´. Ear from notch, dry less than 130 (137
  fresh).


• 
  14. Nape more or less black.


• 
  15. Ears yellow; range Pacific Coastal
  region of Isthmus of Tehuantepec in
  southern Oaxaca and Chiapas.


• 
  Lepus flavigularis, p. 188


• 
  15´. Ears dark buff, grayish, white and
  black; range north of Isthmus of
  Tehuantepec.


• 
  Lepus callotis, p. 186


• 
  14´. Nape gray or grayish buff.


• 
  Lepus gaillardi, p. 188

[Pg 173]

Fig. 44. Distribution of Lepus americanus.

Lepus americanus

American Varying Hare

Total length, 363-520; tail, 25-55; hind foot, 112-150; ear from
notch (dry), 62-70. Upper parts brownish or dusky grayish; hind
feet brownish or white depending on subspecies; winter pelage
white except in certain populations along Pacific Coast; basilar
length less than 67; first upper incisors inscribing an arc of a circle[Pg 174]
the radius of which is less than 9.6 mm. There are two to six young
in a litter according to Orr (1940:59).

Lepus americanus americanus Erxleben.

Lepus americanus bairdii Hayden.

Lepus americanus cascadensis Nelson.

[Pg 175]

Lepus americanus columbiensis Rhoads.

Lepus americanus dalli Merriam.

Lepus americanus klamathensis Merriam.

Lepus americanus macfarlani Merriam.

Lepus americanus oregonus Orr.

[Pg 176]

Lepus americanus pallidus Cowan.

Lepus americanus phaeonotus J. A. Allen.

Lepus americanus pineus Dalquest.

Lepus americanus seclusus Baker and Hankins.

Lepus americanus struthopus Bangs.

Lepus americanus tahoensis Orr.

[Pg 177]

Lepus americanus virginianus Harlan.

Lepus americanus washingtonii Baird.

Lepus othus

Alaskan Hare

Total length, 565-690; tail, 53-104; hind foot, 147-189; ear from
notch (dry), 75-78. Color brownish in summer; white in winter;
but tips of ears always black. General comparisons indicate that
this is the species which, in Eurasia, bears the name Lepus timidus.

Lepus othus othus Merriam.

Lepus othus poadromus Merriam.

[Pg 178]

Lepus arcticus

Arctic Hare

Total length, 480-678; tail, 34-80; hind foot, 132-174; ear from
notch (dry), 70-84. Upper parts gray in summer in southern subspecies;
in others white; in winter white in all subspecies, except
black tips of ears. Weights of lean individuals reach 12 pounds.
Hopping on the hind feet without touching the forefeet to the
ground has repeatedly been recorded for this species. There are
four to eight young in a litter.

Fig. 45. Distribution of Lepus othus and Lepus arcticus.

1. L. o. othus


2. L. o. poadromus


3. L. a. groenlandicus


4. L. a. porsildi


5. L. a. monstrabilis


6. L. a. arcticus


7. L. a. andersoni


8. L. a. labradorius


9. L. a. bangsi

Lepus arcticus arcticus Ross.

[Pg 179]

Lepus arcticus andersoni Nelson.

Lepus arcticus bangsii Rhoads.

Lepus arcticus groenlandicus Rhoads.

Lepus arcticus labradorius Miller.

Lepus arcticus monstrabilis Nelson.

[Pg 180]

Lepus arcticus porsildi Nelson.

Lepus townsendii

White-tailed Jack Rabbit

Total length, 565-655; tail, 66-112; hind foot, 145-172; ear from
notch (dry), 96-113. Upper parts grayish brown; tail all white
or with dusky or buffy mid-dorsal stripe which does not extend
onto back; white in winter in northern parts of its range. Two
adult males weighed 2945 and 2494 grams (Orr, 1940:43) and
there are 3 to 6 young in a litter.

Fig. 46. Distribution of Lepus townsendii.

1. Lepus townsendii townsendii


2. Lepus townsendii campanius

Lepus townsendii campanius Hollister.

[Pg 181]

Lepus townsendii townsendii Bachman.

Lepus californicus

Black-tailed Jack Rabbit

Total length, 465-630; tail, 50-112; hind foot, 112-145; ear from
notch (dry), 99-131. Upper parts gray to blackish; tail with black
mid-dorsal stripe extending onto back; never all white in winter.
On the tableland of Mexico and in the southwestern United States
where this species occurs together with the white-sided jack rabbits,
L. californicus can be recognized by the terminal black patch
on the outside of each ear and by the less extensive area of white
on the flank. To the eastward, in Tamaulipas, where only the black-tailed
jack rabbit occurs, it too, has extensively white flanks and
some individuals lack the terminal black patch on the ear.

A certain means for distinguishing the skulls of the black-tailed
jack rabbit from those of all of the white-sided jack rabbits has not
yet been found. The same is true of the skulls of the white-tailed
jack rabbit and the black-tailed jack rabbit in the Great Basin region
of Nevada. The skulls, at least of adults, of these two species, in the[Pg 182]
region east of the Rocky Mountains can be readily distinguished by
the pattern of infolding of the enamel on the front of the first upper
incisor teeth; L. townsendii has a simple groove on the anterior face
of the tooth and L. californicus, east of the Rocky Mountains, has a
bifurcation, or even trifurcation, of the infold that can readily be
seen by examining the occlusal surface of the incisor.

In Arizona, Vorhies and Taylor (1933:478) found the weight of
23 adult males to average 5.1 (4.4-6.1) lbs. In that state, 70 pregnant
females averaged 2.24 (1-6) young per litter and the authors
(op. cit.) thought that a female had three or four litters each year.

Lepus californicus altamirae Nelson.

Lepus californicus asellus Miller.

Lepus californicus bennettii Gray.

Lepus californicus californicus Gray.

[Pg 183]

Lepus californicus curti Hall.

Fig. 47. Distribution of Lepus californicus and Lepus insularis.

[Pg 184]

Lepus californicus deserticola Mearns.

Lepus californicus eremicus J. A. Allen.

Lepus californicus festinus Nelson.

Lepus californicus magdalenae Nelson.

Lepus californicus martirensis Stowell.

[Pg 185]

Lepus californicus melanotis Mearns.

Lepus californicus merriami Mearns.

Lepus californicus richardsonii Bachman.

Lepus californicus sheldoni Burt.

Lepus californicus texianus Waterhouse.

Lepus californicus wallawalla Merriam.

Lepus californicus xanti Thomas.

Lepus insularis Bryant

Black Jack Rabbit

Total length, 574; tail, 96; hind foot, 121; ear from notch (dry),
105. This insular species, clearly a close relative of Lepus californicus
of the adjacent peninsula of Baja California, is mainly
glossy black on the upper parts but grizzled and suffused on sides
of back and body, and in some specimens on head, with dark buffy
or reddish brown; underparts dark cinnamon buffy or dusky brown;
ears and sides of head grayish dusky; jugals heavier than in Lepus
californicus of the adjacent peninsula of Baja California.

Lepus callotis Wagler

White-sided Jack Rabbit

Total length, 560; tail, 71; length of hind foot, 133; ear from notch
(dry), 117. Upper parts dark, slightly pinkish, buff heavily washed
with black; backs of ears mainly white without terminal patch of
black; flanks white; rump iron gray.

Fig. 48. Distribution of the White-sided Jack Rabbits.

Guide to kinds:

1. Lepus callotis


2. Lepus flavigularis


3. Lepus gaillardi gaillardi


4. Lepus gaillardi battyi


5. Lepus alleni alleni


6. Lepus alleni palitans


7. Lepus alleni tiburonensis

[Pg 188]

Lepus flavigularis Wagner

Tehuantepec Jack Rabbit

Total length, 595; tail, 77; hind foot, 133; ear from notch (dry),
112. Upper parts bright ochraceous buff strongly washed with black;
ears entirely buff; nape with black stripe extending back from base of
each ear and median stripe of buff; flanks and underparts of body
white; rump iron gray; tympanic bullae smaller than in any other
Lepus of México.

Lepus gaillardi

Gaillard Jack Rabbit

Total length, 450-536; tail, 59-80; hind foot, 124-133; ear from
notch (dry), 110-112. Coloration essentially as in Lepus callotis
except that nape is plain buff, without a trace of black, and upper
parts paler, more vinaceous buff.

Lepus gaillardi battyi J. A. Allen.

Lepus gaillardi gaillardi Mearns.

Lepus alleni

Antelope Jack Rabbit

Total length, 553-670; tail, 48-76; hind foot, 127-150, ear from
notch, in flesh, 138-173. Top and sides of head creamy buff, slightly
washed on top with black; tail white except for mid-dorsal line of
black extending onto rump; sides of shoulders, flanks, sides of
abdomen, rump, and outside of hind legs uniform iron gray. The
average weight of 61 adult males from Arizona was 8.2 lbs. In that
state 124 pregnant females had an average of 1.93 young (1-5) and
Vorhies and Taylor (1933:580) thought that a female had three or
four litters per year.[Pg 189]

Lepus alleni alleni Mearns.

Lepus alleni palitans Bangs.

Lepus alleni tiburonensis Townsend.

Lepus europaeus

European Hare

Total length, 640-700; tail, 70-100; hind foot, 130-150; ear from
notch (dry), 79-100; weight, 3000 to 5000 grams. Upper parts
tawny, mixed with blackish hairs on back; underparts white including
underside of tail; upper side of tail and terminal patch at
distal end of outside of ears black; upper side of feet tawny like
sides (not white or whitish). This is an introduced species.

Lepus europaeus europaeus Pallas.

Lepus europaeus hybridus Desmarest.

[Pg 190]

Figs. 49-51. Dorsal views of skulls of hares. All × 1.

• Fig. 49. Lepus americanus tahoensis, 1/2 mi. S Tahoe Tavern,
  Lake Tahoe, Placer County, California. No. 37522 MVZ, .


• Fig. 50. Lepus alleni alleni, Santa Rita Mountains, 30 mi. S
  Tucson, Pima County, Arizona. No. 8621 KU, .


• Fig. 51. Lepus arcticus groenlandicus, Cape Alexander, Greenland.
  No. 114850 USNM, .

[Pg 191]

Figs. 52-54. Dorsal views of skulls of hares. All × 1.

• Fig. 52. Lepus townsendii townsendii, north end Ruby Valley, east base
  Ruby Mountains, Elko County, Nevada. No. 4686, coll. of Ralph Ellis, .


• Fig. 53. Lepus callotis, 3-1/2 mi. S Tecolotlán, Jalisco. No. 31842 KU, .


• Fig. 54. Lepus californicus deserticola, 4 mi. W Fallon, Churchill County,
  Nevada. No. 900061 MVZ, .

[Pg 192]

Figs. 55-57. Ventral views of skulls of hares. All × 1. Different views of
these skulls are shown in figs. 49-51.

• Fig. 55. Lepus americanus tahoensis.


• Fig. 56. Lepus alleni alleni.


• Fig. 57. Lepus arcticus groenlandicus.

[Pg 193]

Figs. 58-60. Ventral views of skulls of hares. All × 1. Different views of
these skulls are shown in figs. 49-51.

• Fig. 58. Lepus townsendii townsendii.


• Fig. 59. Lepus callotis.


• Fig. 60. Lepus californicus deserticola.

[Pg 194]

Figs. 61-64. Lateral views of skulls (one lower jaw) of hares.
All × 1.
Different views of
these skulls are shown in figs. 49-51.

• Fig. 61. Lepus alleni alleni.


• Fig. 62. Lepus americanus tahoensis.


• Figs. 63-64. Lepus arcticus groenlandicus.

[Pg 195]

Figs. 65-68. Lateral views of skulls (one lower jaw) of hares. All × 1.
Different views of these skulls are shown in figs. 52-54.

• Fig. 65. Lepus townsendii townsendii.


• Fig. 66. Lepus callotis.


• Figs. 67-68. Lepus californicus deserticola.

[Pg 196]

LITERATURE CITED

Allen, J. A.

Anderson, R. M.

Anderson, R. M., and Rand, A. L.

Bailey, A. M., and Hendee, R. W.

Bailey, V.

Barnes, C. T.

Black, J. D.

Blair, W. F.

Bole, B. P., Jr., and Moulthrop, P. N.

Borell, A. E., and Bryant, M. D.

[Pg 197]

Brown, L.

Burt, W. H.

Burt, W. H., and Hooper, E. T.

Cahalane, V. H.

Cary, M.

Cockrum, E. L.

Cowan, I. McT.

Dalquest, W. W.

Davis, W. B.

Davis, W. B., and Robertson, J. L., Jr.

Dellinger, S. C., and Black, J. D.

[Pg 198]

Dice, L. R.

Durrant, S. D.

Enders, R. K.

Goldman, E. A.

Goodwin, G. G.

Hall, E. R.

Hall, E. R., and Bowlus, H. L.

Hall, E. R., and Kelson, K. R.

Hall, E. R., and Villa R. B.

Hamilton, W. J., Jr.

Handley, C. O., Jr., and Patton, C. P.

[Pg 199]

Harrison, T., and Nickie, P. F.

Hill, J. E.

Hoffmeister, D. F.

Hooper, E. T.

Howell, A. H.

Huey, L. M.

Kellogg, R.

Langenbach, J. R., and Beule, J. D.

Leopold, A. S., and Hall, E. R.

Linsdale, J.

Llewellyn, L. M., and Handley, C. O.

[Pg 200]

Lowery, G. H., Jr.

Lyman, C. P.

Lyon, M. W., Jr.

Manville, R. H.

Martin, K.

Miller, G. S., Jr.

Necker, W. L., and Hatfield, D. M.

Nelson, E. W.

Orr, R. T.

Osgood, F. L., Jr.

Over, W. H., and Churchhill, F. P.

Palmer, R. S.

Peterson, R. L.

Philip, C. B.

Rausch, R.

Rust, H. J.

[Pg 201]

Schantz, V. S.

Severaid, J. H.

Sherman, H. B.

Sherman, F.

Silver, J.

Snyder, L. L., and Logier, E. B. S.

Soper, J. D.

Southern, H. N.

Stead, D. G.

Surber, T.

Swanson, G., Surber, T., and Roberts, T. S.

Taylor, W. P., and Shaw, W. T.

Vorhies, C. T., and Taylor, W. P.

Warren, E. R.

[Pg 202]

Wodzicki, K. A.

Transmitted May 8, 1951. Museum of Natural History, University
of Kansas, Lawrence, Kansas.

23-7988