134 PROCEEDINGS OF THE ACADEMY OF 



Diarj. Superior incisors with a single strong deep groove lying 

 wholly in the inner half of the tooth. Tail and hind feet naked 

 or nearly so. Forefeet, including claws, decidedly shorter than 

 the hind feet. Pouches moderate, reaching scarcely or not be} T ond 

 the head. Pelage peculiarly stiff, harsh, coarse and nearly lustre- 

 less. Color uniform dull chocolate-brown, merely paler below. 

 Of largest size; upward of a foot long; tail only about 3 inches; 

 sole of hind foot 1.66. 



Hab. Parts of Mexico, and Central America. 



II. Genus THOMOMYS, Maxim. 



Oryctomys, pt., Eyd. and Gerv., Mag. Zool. vi. 1836, 23. 

 Thomomys, Maxim., N. Act. Ac. C. L. xix. 1839, 383. 



In addition to the foregoing, all the synonj-ms of Geomys (q. v.) 

 have been applied to species of this genus. 



It is impossible to diagnosticate more than two species of this 

 genus. The expressions used, therefore, to distinguish the three 

 intergrading geographical races of T. talpoides, in the following 

 analysis, must be understood to indicate onty the normal average 

 of the three forms, perfectly intermediate examples of each of 

 which are found. 



Analysis of Species. 



A. Large ; adults at least six inches long, usually more. Hind foot 

 an inch or more long. Tail at least one-third as long as head and 

 Lod} r . Above brown, reddish, etc, ; below gray, brown, reddish, 

 etc. (not white). Ears set in a blackish area. 1. talpoides. 



a'. Six or eight inches long. Fore claws highly developed (0.45- 

 0.50 long) causing the hand to about equal the foot in length. 

 Color of the house rat, with white tail and feet ; usually white 

 about the mouth. Northern Interior. a. talpoides. 



b'. Seven to nine inches'long ; fore claws less developed, usually 

 under 0.50, leaving the hand shorter than the foot ; reddish- 

 brown, the belly muddy brownish ; tail and feet usually not 

 entirely white ; mouth-parts dark, contrasting with the white 

 of the pouches. Pacific coast, U. S. b. bulbivorus. 



rj . Averaging smaller ; usually six to seven inches long. Fore 

 claws about 0.40 long, leaving the hand decidedly shorter than 



Museum, who, with his usual courtesy, examined Gray's type for me, and 

 found it to agree exactly with the diagnosis I sent him of O. Mspidus. In 

 this identification he is supported by Mr. Gerrard, who examined the origi- 

 nal specimen with him. 



