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BULLETIN UNITED STATES GEOLOGICAL SUEVEY. 



mens have all been taken while returning from a foraging trip, but such 

 is not the case. 



The Pouched Gopher in this region is found in towns or villages, much 

 resembling the Prairie Dog towns, so familiar to all observers in many 

 sections of the Korthwest, with the exception that their burrows have 

 no external openings, these being carefully closed by the animal. 



There is ordinarily no difficulty in capturing this animal by judicious 

 use of steel traps that do not require much pressure to spring ; and to 

 the failure to comply with this requirement is, I believe, mainly to be 

 attributed the ill success of most collectors 5 although there is a period 

 in addition to the winter months (which is here found to be from about 

 the middle of June to the end of August) when the acquisition of speci- 

 mens is attended with great difficulties. No doubt but at this time the 

 parents are to a great extent engaged in rearing their young, and 

 scarcely ever emerge from their subterranean homes. I have, however, 

 seen a very few quite young specimens by the middle of June; but I 

 believe the greater majority are brought forth between the middle of 

 June and the end of August, and that but one litter is brought out each 

 year. 



The diagnostic value of the markings of the upper incisors, as pointed 

 out by Dr. Ooues in his admirable review of Geomys and Thomomys, is 

 confirmed in my specimens. The groove, or sulcus, nearly bisecting the 

 incisors, is more distinct in the young than in the old, becoming more 

 shallow in proportion to the age of the animal, and in very old speci- 

 mens I can detect no sign of the third groove of Coues, although in 

 many of the young and middle-aged it is distinctly perceptible. 



The measurements of the specimens taken here are as follows : — 



