56^ Life-histories of Northern Animals 



backward in the burrow; in each cheek is an enormous fur- 

 Hned pocket or pouch, that opens in front outside of the mouth. 

 The genus Thomomys (Wied., 1839) answers to the fore- 

 going, and has also the front upper teeth without a central 

 groove. Dentition: 



Inc. ; prem. ; mol. =20 



i-i i-i ^-7, 



GENERAL In additiou to all the Family and generic characters, the 



ACTERs Gray Pocket-gopher has the tail less than half the length of the 

 head and body; the female has 6 pairs of teats, 2 under the 

 fore-legs, 2 on the chest, and 2 on the lower belly. The 

 species has also marked peculiarities of size and colour. 



SIZE This is one of the largest members of the genus. A male 



taken at Carberry, Man., October 31, 1886, measured total 

 length from snout to tail tip, 9! inches (244 mm.); head and 

 body, 7 inches (178 mm.); tail, 2| inches (73 mm.). The 

 hind-foot is about i\ inches (32 mm.). 

 The females are smaller. 



COLOUR The colour is a dark grayish, becoming browner on the 



back, and pale slatey below; nearly white on chin, throat, feet, 

 and tail. It is difficult to describe the colour exactly, especially 

 as there is a good deal of individual variation, but talpoides 

 may be distinguished from its nearest neighbours by its greater 

 size and darker colours. 



Two races are recognized: 



talpoides Richardson, the typical form. 

 rufescens Wied., redder in colour. 



Life-history. 



RANGE Map 2>?> shows the range of the Family Geomyidce to 



which the Pocket-gopher belongs. The various species are 

 found in the whole of the region west of the Mississippi Valley, 

 as far as the Pacific Coast, south well into Mexico and north 

 at least as far as the Saskatchewan; thus they are found 

 throughout a region of about 2,000,000 square miles. 



