SCIURID®—SPERMOPHILUS TERETICAUDUS. 863 
SPERMOPHILUS TERETICAUDUS Baird. 
Fort Yuma Spermophile. 
Spermophilus tereticaudus BArrp, Mam. N. Amer. 1857, 315; U.S. and Mex. Bound. Survey, ii, pt. ii, 1859, 
33, pl. vii, fig. 2, head and feet; pl. xxii, fig, 4, skull—ALLEN, Proc. Bost. Soc. Nat. Hist. 
xvi, 1874, 291. 
Speciric cuars.—Length of head and body about 6.00; of tail to end 
of vertebrae 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 vertebre 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. spidosoma, 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 TERETICAUDUS. 
| 
B ; ° 
3 From tip of nose to— Tail to end Length of— ag 
a of— : 8 
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AVA) Yaa ees OF. 0 |e ee er © | 0.55 | 1.14 | 1.00 | 4.10} 2.80 | 3.27 | 0.75 | 1.20 | 0.10 | Alcoholic. 
Uy esse WD) Bresecocmascrinncnne rescore Os do | 0.68 | 1.28 | 1.58] 6.08 | 3.C0 }...-.. 0:90 |} 1.30 }.-.... Se eOs 
1584 |....-. GD) ee eR Oanon eeSao eee | eee eee | 1.60 | 5.25 | 4.42 | 4.84 |...... RGSO ivoe cto aaesG0s 
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