34 
IT. S. P. R. R. EXP. AND SURVEYS—ZOOLOGY-GENERAL REPORT. 
SOKEX THOMPSON!, Baird. 
Sp. Ch.—V ery small and slender. Ears large, about as long as the fur, -which measures 1J lines. Feet very small and 
slender ; hinder ones barely exceeding four lines. Tail shorter than the body, exclusive of head ; terminated by a pencil. 
Only four lateral teeth above, the third in contact with the first molar. Anterior upper incisor with a serrated internal 
lobe near the point. 
Color above, dark olive-brown, slightly hoary; paler on sides. Beneath, ashy white. No tinge of chestnut or reddish 
brown. Length, 2 inches. Tail, 1£. 
Description of a Specimen in Alcohol, No. 1686.—Size very diminutive ; body slender. Head 
narrow, pointed, though the muzzle is broad, depressed, and the tip naked and bilobed. The 
ear opening is large, the antitragus, helix, and concha, well developed ; their'edges well mar¬ 
gined with hairs ; the concha is nearly as long as the adjacent hair. 
The tail is slightly constricted at the base, rather thin throughout, and appears depressed ; 
it is well covered with hair concealing the annuli, and ends in a distinct pencil. It is about as 
long as the body, exclusive of the head. 
The feet are very diminutive ; the posterior measuring but 0.35 of an inch, and a little broader 
than the anterior ; their soles appear hairy for the posterior third, but there is a narrow naked 
central line only overlapped by the hairs ; the six plantar tubercles are very large and con¬ 
spicuous among the smaller ones. There is no distinct ciliation to the feet. 
The color above is an olive-brown, with a hoary intermixture, caused by a lighter penultimate 
annulus to the hair. Beneath, ashy white ; a faint yellow-brownish tinge under the throat. 
Feet and under surface of the tail, whitish. Teeth of a deep pitchy chestnut color almost to 
the roots. 
Measurements of 1686. 
Inches. 
Inches. 
Nose to eye_ 
. 27 
Tail to end of hair.. 
1. 27 
Nose to ear_ 
. 55 
Fore foot_ 
. 21 
Nose to occiput___ 
. 72 
Hind foot 
. 36 
Nose to root of tail__ 
1. 70 
Ears from anterior base to most remote point.... 
.22 
Tail to end of vertebra?_ 
1.12 
Weight, 21. 984 grains. 
Description of a dried skin .—Body very slender. Snout much elongated. Ears quite large, 
with a considerable naked region about the meatus, although the ears are moderately well furred 
elsewhere. They are nearly or quite as long as the fur, which, on the back, measures about 
one and a half lines. The feet are very small, short, and narrow, absolutely less than in any 
species examined by me; the anterior contained a little over one and a half times in the hinder 
ones. The lateral claws behind attain the penultimate articulation of the adjacent toes. 
The tail is a little less than the body exclusive of the head ; it is very slender, well furred, 
and ends in a pencil of bristly hairs. 
