136 PROCEEDINGS OF THE ACADEMY OF 



much of the chin, throat, and breast also white in irregular patches, 

 where the fur is white to the base. No sooty blackish about the 

 mouth-parts ; no obvious distinction in color between the pouch 

 and its surroundings ; no strongly pronounced reddish-brown on 

 the under parts. General tone of coloration not decidedly tawny. 

 Ears set in a small blackish area. Length 6-8 inches ; tail 3 

 inches or less, decidedly less than half the length of the head and 

 body. Fore and hind feet, claws included, approximately equal 

 to each other, about 1.25 ; longest fore claw little less than the 

 length of the rest of the hand, about 0.50. 



(Obs. The foregoing are the average subspecific characters of 

 this geographical race as distinguished from the next, with which 

 it intergrades.) 



Nab. Supposed to occur in the interior of North America 

 from " Hudson's Bay" to the " Columbia River," and to occupy 

 about the northern half of the United States west of the Mis- 

 sissippi, exclusive of the Pacific coast region being replaced 

 there by T. bulbivo?~us, and to the south by T.umbrinus. (Speci- 

 mens examined from the Assiniboine country; from Selkirk Set- 

 tlement; from Minnesota westward along the parallel of 49 N. 

 to the Rocky Mountains; and from Idaho, Wyoming, Utah, and 

 Nevada.) 



la. Thomomys talpoides bulbivorus (Rich.), Coues. 



Diplostoma? bulbivorum, Rich., F. B. A. i. 1820, 20G, pi. 18 B. 



(Lettered " douglasii.") 

 Ascomys bulbivorus, Wagn., Suppl. Schreb. iii. 1843, 387. (Compiled.) 

 Geomys bulbivorus, Lee, these Proceedings, 1852, 162. (Compiled.) 

 Pseudostoma bulbivorum, A. & B., Q. N. A. iii. 1854, 337. (Com- 

 piled.) 

 Geomys {Thomomys) bulbivorus, Gieb., Saug. 1855, 530. (Compiled.) 

 Thomomys bulbivorus, Baird, M. N. A. 1857, 389, pi. 50, f. 3 a-g, pi. 



52, f. 1 a-g. 

 Geomys douglasii, Rich., F. B. A. i. 1829, 200, pi. 18 C, f. 1-6. 

 Ascomys douglasii, Wagn., Snppl. Schreb. iii. 1843, 392. (Compiled.) 

 Pseudostoma douglasii, And. & Bach. Q. N. A. iii. 1853, 24, pi. 105. 

 Geomys {Thomomys) douglasi, Gieb., Sang. 1855, 531. (Compiled.) 

 Thomomys douglassit, Bd. M. N. A. 1857, 394. 

 Oryrtomys (Saccophorus) bottom, Eyd. & Gerv., Mag. Zool. vi. 1836, 23, 



pi. 21, f. 4. 

 Thomomys bottce, Less., Nouv. R. An. 1842, 119. (Compiled.) 

 Geomys fuliginosus, Schinz, Syn. ii. 1845, 136. (Mere change of name.) 

 Thomomys laticeps, Baird, these Proc. 1855, 335 ; M. N. A. 1857, 392. 



