368 U. Ss. P. R. R. EXP, AND SURVEYS—ZOOLOGY—GENERAL REPORT. ~ 
GEOMYS, Rafinesque. 
Geomys, Rarinesque, Amer. Monthly Magazine, If, November, 1817, 45. 
Diplostoma, Rar.—Is. (in part ) 
Saccophorus, Kuni, Beitrige, 1820, 65. 
Pseudostoma, Say, Long’s Exped. R. Mts. I, 1823, 406. 
Aup. & Bacu. N. Am. Quad. I, 1849. 
Ascomys, Licutenstein, Abh. Berl. Akad. for 1822—’23, (1825,) 20. 
Branrs, Het Geslacht der Muizen, 1827, 23. 
Waener, Suppl. Schreber, III, 1843, 380. 
A large groove near the central line of the upper incisor. ‘Skull large and massive ; zygomata thickened. Anterior upper 
molar, with the two lobes elliptical, much elongated transversely and approximated, nearly equal. Middle two with the outlines 
regularly elliptical. Posterior lower molar sub-elliptical. Ears obsolete. 
a. A second fine groove near the inner edge of upper incisors. Fore feet much larger than the hinder ones, Third claw of 
hand greatly developed; second claw reaching only to the middle of the fourth. 
b. Only one groove on or near the central line. Fore and hind feet nearly equal. Third claw much developed ; second 
claw and finger nearly as long as the fourth claw. 
Form of body thick-set, cylindrical ; heaviest anteriorly, especially about the head. There is 
no indication of a neck; on the contrary, the thickest portion is at the back part of the head, 
from which the body tapers gradually to the tail, widening a little across the thighs. The 
nostrils are small, elliptical, with a papilla above ; they are quite distant apart, situated laterally 
on each side of a blunt muzzle. This muzzle has a broad furrow down the middle, with 
aslight ridge at the bottom of the furrow. The muzzle is bounded above by a horizontal 
furrow having an overhanging ridge, which is coated with short hairs at its upper portion. 
The upper lipis not cleft, but passes almost directly in a straight or slightly concave line across 
the bases of the incisors ; the space between this outline and the naked muzzle (almost as high 
as the muzzle itself) being coated with short hairs. 
The opening of the mouth is quite diminutive, although there is an anterior chamber behind 
the incisors which narrows behind to the true mouth. The skiu lining this chamber (which 
extends above almost as far back as the molars) is covered with short hair, except, perhaps, just 
back of the upper incisors, where there is a naked space bounded by a short fold of skin. The 
lower lip is tumid, quite free, and capable of much motion round the incisors. The upper wall 
of the cheek pouches begins at a point which forms an equilateral triangle with the end of the 
upper incisors and the nostril; it ends about opposite the posterior extremity of the lower side 
of the lower jaw. The plane of the opening is nearly parallel with the vertebral line. The 
pouch runs back to the middle of the scapula, and is capable of much distension. It is well 
clothed with hair on the side next the head ; on the other it is nearly naked with a few scattered 
hairs. Theears are very rudimentary, represented only by a thickened ridge of skin, narrowest 
above and widening below. In drying, this ridge disappears almost entirely. The tail is 
thickened, though tapering somewhat to the tip, which is blunt and naked for about half an 
inch, and appears to possess some degree of tactile sensibility, as in the opossum. It is hairy, 
except at the end. 
The upper surfaces of all the feet are covered with short hairs, but they are perfectly smooth 
and rather tumid below. There is a very large tubercle at the base of the palm, divided by a 
longitudinal groove which passes round behind the inner smaller portion. From the posterior 
