Family Ochotonidae 
53 
between the Grand and White Rivers, which is no doubt occupied 
by the Rocky Mountain Cottontail. 
Habits. — In the localities where I have had an opportunity 
to observe this species it was found in the sage-brush and 
greasewood of the mesas and bottoms; among the rocks 
of the hillsides and caflons; and in the cedar and pinon woods; 
any place seemed to suit it. The breeding season begins 
in March in Montezuma County. 
Family OCHOTONIDiE 
Small Guinea-pig-like forms with small eyes, broad and 
round ears, and subequal limbs with five toes in front and four 
behind, and no external tail; skull depressed and without 
postorbital processes; incisors large, the upper ones deeply 
grooved in front; molars as in Leporidce. 
A small family containing only one genus, found at con- 
siderable elevations in Asia and North America. 
Genus OCHOTONA (Mongol name of the Pika) 
Ochotona Link, Beitr. Nat., i., pt. ii., p. 74 (1795). Type O. 
ochotona. 
Revision, Lyon, Smithson. Misc. Coll., xlv., pp. 321-447 (1904). 
Skull above broad posteriorly, with a slight sagittal crest narrow- 
ing anteriorly ; anteorbital constriction considerable ; malar pro- 
longed almost to auditory opening ; dentition, i.f;p. |; m. fX2=26; 
upper incisors broad, long and with a deep groove on the outer 
side, dividing each tooth into unequal halves, and terminating in 
two points, the cutting edge being deeply notched and gouge-shaped 
instead of chisel-shaped ; lower molars deeply grooved on the sides, 
causing the salient angles to be very prominent. 
Alpine and Boreal animals, found in both the New and Old 
Worlds. Seven species are known in North America, one 
only in Colorado, 
