APPENDIX C. — MAMMALS. ' 813 



thighs. The dorsal line is inconspicuous, except on the darker 

 tips of the short mane. 



Circumference of horn at the base 17 inches. 



Length of horn along the convexity 36^ *' 



Distance between the tips of horns 18 " 



The bighorn, at one time erroneously supposed to be the same 

 as the old-world argali, is common in the ranges and hills be- 

 longing to the Rockj Mountain system. 



COLLECTED BY LIEUTENANT ABEKT. 

 1. PSEUDOSTOMA CASTANOPS, Baird. 



'? 



This beautiful species was collected by Lieutenant Abert along 

 the prairie road to Bent's Fort. In general colour it is of a pale 

 yellowish-brown, with an ample patch of light chestnut on the side 

 of the head and face, deepest above. The dorsal line is not darker 

 than the rest of the fur. In size it is intermediate between P. 

 horealis and bursarius. 



The colour of the fur above is slightly grizzled, and much lighter 

 than in P. bursarius ; beneath, paler. Throat, space between the 

 forelegs and sides of arms, pale rusty. The chestnut marking, 

 on the side of the head, is very strongly defined, occupying on 

 each side a nearly circular space of about one and three-quarter 

 inches in diameter, with the nearly obsolete ear as a centre. 

 These chestnut spaces do not quite meet on the crown and occiput, 

 but leave a rectilinear interval, coloured like the rest of the back, 

 of about one-eighth of an inch in width. On the muzzle, however, 

 from above the eyes, the colour of opposite sides is confluent. 



The hind feet and toes are thinly covered with whitish hairs, 

 which on the fore feet appear more ferruginous. The claws are 

 white, but sufficiently transparent to allow the coagulated blood in 

 the phalanges to show through them. 



Length to base of tail (approximate) 8 inches. 



Tail 2| " 



Hand (along the palm) l^^j " 



Length of exposed part of middle anterior claw. ^ 

 Hind feet (along sole) from heel 1 j% 





Middle claw \l " 



