Leporidae 
31 
Revision, Lyon, Smithsonian Miscell. Coll., xlv., pp. 321-447 
(1904). Nelson, North American Fauna, No. 29 (1909). 
Skull high, superior outline much curved, especially at occipital 
region; supraorbital usually more or less broadly wing-like and 
subtriangular in outline, the posterior process in the majority of 
species long, more or less divergent, flanking a deep, wide notch, 
the posterior extremity sometimes completely fused with skull, 
sometimes not ; interparietal not persistent in adult ; all the openings 
of the skull are large; orbits very large, meeting in the mesial 
line of the cranium; dentition, i. f ; p. |; m. f X 2 = 28; incisors 
deeply implanted in the jaws, molars rootless; third upper molar 
minute; last lower molar large, but still much the smallest of the 
lower series; front feet with five toes, hind feet with four; hind legs 
elongated, in some species greatly so. 
Members of the genus are found all over North America 
from the Arctic regions southward through Mexico as far as 
the State of Chiapas. Many species and subspecies have 
been described, Nelson's recent paper recognizing 43 species 
and subspecies, of which five have been reported from 
Colorado. 
Key of the Species 
A. Size small, length about 17; hind foot comparatively long, 
5.75; ear short, 2.75; turns white in winter. 
L. biirdi, p. 38 
B. Size large, length 22-24; ears long, 4.25-5.75. 
a. Profile of skull high and arched; rostrum short and deep; tail 
white on upper surface, or with but little black;, winter 
pelage lighter in color than the summer, often white, 
a'. Head and body above yellowish gray; black patch on tip 
of ears broader. L. campestris, p. 32 
b'. Head and body above dull grayish; black patch on tips of 
ears narrower. L. campestris townsendi, p. 37 
b. Profile of skull low and flattened; rostrum long and com- 
paratively shallow ; upper surface of tail with large black 
area ; winter pelage about the same as the summer. 
(Subgenus Macro tolagus.) 
a^ upper parts, including ears, rich ochraceous buffy gray; 
rump patch strongly marked; ears shorter, about 4.25. 
L. californicus melanotis, p. 41 
b'. Upper parts gray with a slightly buffy tinge; gray rump 
patch fairly well marked; ears longer, 4.75-5.25. 
L. californicus texianus, p. 43 
