SCIURIDyE— SPERMOPHILUS TEBETIOAUDUS. 



863 



SPERMOPHILUS TERETICAUDUS Baird. 



Fort Yuma Spermophile. 



Spermophilus tereticaudus Baikd, Mam. N. Amer. 18">7, 315; U. S. and Mex. Bouud. Survey, ii, pt. ii, 1859, 

 3H, pi. vii, fig. 2, bead and feet; pi. xxii, fig. 4, skull. — Allen, Proc. Host. Soc. Nat. Hist. 

 xvi, 187*4, 291. 



Specific chars. — Length of head and body about G.00 ; of tail to end 

 of vertebras 3.60 to 4.40 ; to end of hairs about 4.75. Above, finely varied 

 with yellowish-brown and gray, without distinct spots; beneath, pale brown- 

 ish-white. Tail above, concolor with the back, with indistinct annulations, 

 and a faint, subterminal, dusky bar; color below like that of the ventral 

 surface of the body. Ears very small, nearly obsolete. Tail slender, not 

 appreciably flattened, the vertebrae alone rather more than half the length 

 of the head and body. Soles and muzzle densely pilose. Differs very little 

 in general proportions from S. mexicanus, but is considerably smaller, its size 

 being nearer that of »S'. spilosoma, which it almost exactly resembles in cranial 

 characters. It differs from it radically in coloration and in its much longer 

 and more slender tail. 



The peculiar combination of characters presented by this species renders 

 it very distinct from its nearest allies, S. mexicanus and S. spilosoma. It wholly 

 lacks the reddish coloration and distinct white spots that characterize these 

 species, while its tail is more terete and the general form of the body perhaps 

 rather more slender. It is known as yet only from the specimens described 

 by Professor Baird in his original account of the species, published twenty 

 years ago. These were all collected at Fort Yuma, Cal., by Maj. G. H. 

 Thomas. They consist of one skin and a skull and three examples in alco- 

 hol, all in rather bad condition. 



Table CVI. — Measurements of three specimens of Spermophilus tep.eticaudus. 



