GEOMYID.E— THOMOMYS TALPOIDES. 



625 



Habitat. — 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 Mississippi, exclusive of the Pacific 

 Coast region ; being replaced, to the west, by T. bulbivorus, and, to the south, 

 by T. umbrinus. (Undoubted specimens seen from Selkirk Settlement, British 

 America ; from Minnesota westward through Dakota and Montana to the 

 Rocky Mountains ; and from Idaho, Wyoming, Utah, and Nevada.) 



Table II. — Measurements of eight fresh specimens of THOMOMYS talpoides. 



Note.— The first five foregoing specimens, all adult, taken the same .season (June to September, 1873), were carefully 

 measured in the flesh by myself. Other specimens, from the same region, not measured in the flesh, cany the limits of totaj 

 length from about 6 to about 8 inches, with a corresponding range of variation in other parts. The tail is taken from its 

 true base — it appears about half an inch shorter in the dried state. The weight of these specimens ranges from 6 to 7 ounces. 

 The girth of the chest is about 5 inches ; of the belly, 6.50. No. 11517, 9, has 12 teats — 2 pairs axillary, 2 pjtirs pectoral, 2 

 pairs inguinal. "When fully distended, in the fresh state, the width across the cheek-pouches is the greatest diameter of the 

 body. Nos. 1, 2, 54 (orig. nos.), all adult, were measured in the flesh by the collector, Dr. C. E. McChesney, U. S. A. The 

 measurements of tail seem to have been taken by him from its apparent base. 



The most northern specimen I have seen is from the Assiniboine River; 

 the species is supposed to range from Hudson's Bay to the Rocky Mountains 

 in British America (northern limit unknown). In the United States, I have 

 specimens from Minnesota, Dakota, Montana, Idaho, Nebraska, Wyoming, 

 Nevada, and Utah. The southern limit is inferred to be somewhere along 

 the middle of the United States. Its range may not inosculate with that of 

 T. umbrinus ; at any rate, I have seen no intermediate specimens from any- 

 where in the Interior, the approach to imibrinus seeming to be made in the 

 Pacific province, through bulbivorus. True talpoides exists fairly westward 

 of the main chains of the Rocky Mountains; but no Thomomys of this style 

 is known from immediate Pacific slopes. It meets and inosculates with the 

 Northern style of bulbivorus ("douglasi") in the Columbia River region. 



This animal is -elaborately described, and its synonymy fully discussed 



in the original memoir. 

 40 m 



