NATURAL SCIENCES OF PHILADELPHIA. 293 



Perognathus monticola, Baird. 



Perognathus monticola, Baird, M. N. A. 1857, 422, pi. 51, figs. 3a-h (St. 

 Mary's, R. Mts.). Suckl., P. R. R. Rep. xii. pt. ii. 1860, p. 101 (notice 

 of the same specimen). 



Diagn. (No. 1251, 9 , Fort Crook, Cala., J. Feilner.) Size of Mus 

 musculus. Tail, including haivs, an inch longer than the head 

 and body, the vertebras alone over half an inch longer. Hind foot 

 nearly one-third as long as head and body; naked strip on sole 

 very narrow posteriorly ; antitragus with a great, flat, rounded, 

 upright lobe, but no lobe of tragus opposite, the notch being de- 

 fined in front by the outer edge of the ear itself. Tail not penicil- 

 late nor crested ; rather thinly but nearly uniformly haired 

 throughout. Pelage very soft and smooth for this genus much 

 as in Cricetodipus. Color of upper parts descending on the fore 

 leg to the wrist. A fulvous lateral stripe, indistinct but evident ; 

 hairs of under parts pure white to the roots ; tail bicolor. Above 

 yellowish-cinnamon lined with blackish, the latter predominating; 

 below, white. Length 2.50 ; tail vertebrae 3.20 ; hind foot 0.80. 



Hab. St. Mary's Mission, W. of Rocky Mts. to Otter Creek, 

 Utah, and Fort Crook, California. 



Description. The generalities of form of this animal are much 

 the same as those of its nearest allies. In relative leno;th the tail 

 nearl} r equals that of P. penicillatus, but it is uniformly haired 

 throughout, without indication of crest or penicillation. The 

 soles are not so extensively denuded as those of P. penicillatus, 

 owing to encroachment of hairs from the sides ; still there is a fairly 

 naked strip to the extreme heel. The tuberculation of the palms 

 and soles, and the proportions of all the digits, are substantially 

 as in that species. The animal is much smaller than any other 

 species of the genus, not much exceeding a Cricetodipus in size. 

 But the most remarkable character is found in the structure of 

 the ear it is singular how sharply distinguished some species of 

 the genus are in this respect. In P. penicillatus a sharp teat-like 

 projection of the antitragus defines the notch posteriorly, and 

 opposite to it on the other side of the notch, there is a similar but 

 smaller prominence of the tragus bounding the notch anteriorly ; 

 thus the external edge of the ear itself is altogether excluded 

 from formation of the notch. Now in P. monticola, the lobe of 

 the antitragus is a broad, flat, upright flap, both relatively and 

 absolutely larger than that of P. penicillatus, but there is no cor- 



