332 [April, 



1 8-12ths inches. Skull 2 3-12ths inches* Collected by J. H. Clark, on Devil's 

 river, Texas. 



Sciurus castanotus, Baird. Size that of <S. cinereus, or larger. Five 

 permanent upper molars. Tail about as long as the body, not bushy. Ears 

 clothed with rather short hairs, not tufted. Soles naked. 



Color. Back deep chesnut brown. Sides and rest of upper parts mixed ash, 

 gray and lead color. Eyelids, upper surface of feet and whole of under parts 

 white. Ears and sides of the head ash-gray. Tail white beneath, and all round 

 the margins and tip. The hairs on the upper surface of the tail are black at the 

 base, then white, then black, with white tips the black predominating ; in one 

 specimen these hairs are entirely black, except at the tip. Head and body 

 12 inches ; tail vertebrae 11 inches ; to end of hairs 12f inches. Hind feet from 

 heel 2 7-l2ths inches. Length of skull 2 4|-12ths inches. 



This species differs from S, aberti in the absence of tufts to the ear, greater 

 extent of chestnut brown on the back, clear white and black of the tail, with 

 few annulations, &c. 



Collected on the Mimbres, by J. H. Clark. 



Tamias dorsalis. Baird. About the size of T. lysteri. Sides of the head 

 with the stripes of Tamias, but more strongly defined than usual. Tail verte- 

 bras not quite half the length of the body; the caudal hairs unusually long, black 

 and chestnut color, largely tipped with white. Body above hoary, mixed with 

 rusty and brown; beneath dull white. Sides and buttocks dull rusty. A single 

 distinct dorsal dark stripe, the others obsolete, except the exterior one on either 

 side, which is rather more evident. Body and head 5 inches. Tail vertebrae 

 2 inches; to end of hairs 3 5-12ths inches. Hind feet from heel 1 3-l2ths inches. 



Collected on the Mimbres by J. H. Clark. 



Spermophilus spilosoma, Bennet. Erroneously considered by Audubon and 

 Bachman to be the young of S. mexicanus. 

 Collected at El Paso by J. H. Clark. 



Spermophilus couciiti, Baird. General character sciurine, like S. beecheyi 

 and douglassi. Color entirely and everywhere black. Thumb with a broad 

 blunt nail. Soles of feet naked. Tail about two-thirds the length of body, 

 with long coarse hairs. Head and body 10 inches. Tail to end ot vertebrae 5 

 inches; of hairs 6| inches. 



Collected in Santa Caterina, Mexico, by Lieut. Couch, and at Victoria by Dr. 

 Berlandiere. 



Perognatus flavhs, Baird. Much smaller than the common house mouse, 

 (Mus i/iusculus.) Tail nearly equal to or less than the body ; scarcely differing in 

 color above and below. Hind feet short. 



Color. Above yellowish buff, with dusky tips to some of the hairs; paler and 

 clearer on the sides. Beneath snowy white to the roots of the hairs. Hairs on 

 the back plumbeous only on their basal half. Head and body 2 2-12ths inches. 

 Tail to end of vertebrae 2 inches. Hind foot from heel 7 inches. 



Collected at El Paso by J. H. Clark. 



Geomys clarkii, Baird. Upper incisors with a single deep groove on the 

 median line of the anterior face; the portions on either side similar. Fore feet 

 nearly equal to or a little shorter than the hinder. Second claw of the hand 

 reaching as far as the fourth. Cheek pouches small. Fur soft and full. 



Color. Above uniform yellowish brown, the hairs with dusky tips. Beneath 

 paler, with strong tinge of gray. Cheek pouches without blotches, and similar 

 to the adjacent regions. Head and body b inches. Tail to end of vertebrae 2 

 inches, the portion covered with very short Lairs 2 2-12 inches. Hind foot, 

 from heel, 1 3-l2 inches ; middle claw 7 lines. 



Collected at Presidio del Norte, on the Rio Grande, by J. H. Clark. 



Tho.momvs umbrinijs. Geomys unibrinus, Rich. Specimens, most probably 

 of this species, were collected by Mr. Clark at El Paso. 



