3l6 VERTEBRATE ANIMALS OF THE UNITED STATES 



with 2 grooves; very common; i litter annually of i to 7 young: upper 

 Mississippi Valley; southward to eastern Kansas and southeastern 

 Missouri; westward into the Dakotas; eastward to Lake ^lichigan. 



G. breviceps Baird. Color dark russet brown; length 230 mm.; tail 

 70 mm. ; hind foot 28 mm. ; size small: lower Mississippi Valley and Gulf 

 coast of Louisiana and Texas; northward into Kansas. 



Subspecies oJ'G. breviceps 



G. b. sagittalis Merr. Size smaller: Gulf coast about Galveston Bay. 



G. b. attwateri Merr. Size larger: coastal plain and islands from 

 Nueces Bay to Matagorda Bay. 



G. texensis Merr. Color dark brown mixed with black; feet and 

 under parts white; length 203 mm.; tail 60 mm.; hind foot 28 mm.: 

 central and southern Texas. 



G. arenarius Merr. Colors pale; length 258 mm.; tail 88 mm.; hind 

 foot 33 mm.: valley of the upper Rio Grande. 



G. lutescens (Merr.). Colors pale drab or fulvous; beneath whitish; 

 length 270 mm.; tail 85 mm.; hind foot 32 mm.: Great Plains from 

 South Dakota to Texas; eastern Wyoming and Colorado ; Upper S6noran 

 zone. 



2. Cratogeomys Merriam. Upper incisors with a single groove: 

 I species in the United States. 



C. castanops Baird. Color yellowish brown; buff beneath; length 

 262 mm. ; tail 65 mm. ; hind foot 37 mm. : Great Plains from the Arkansas 

 River into Mexico. 



3. Thomomys Wied. Outer surface of upper incisors not grooved 

 or with one faint groove near the median margin (Fig. 174) ; ears distinct 

 but very small ; claws moderate : many species, all in the Rocky Moun- 

 tain or Pacific States or along the Mexican border. 



T. boUcE (Eydoux and Gervais). Color yellowish brown, darker 

 towards the head; lips and lining of the pockets white; length 260 mm; 

 tail 89 mm.; hind foot 33 mm.; mammae 4 pairs: CaHfornia; 13 

 subspecies. 



Subspecies of T. bottce 



T. b. botlce (E. and G.). Coast region from Freestone to San Diego. 



T. b. laticeps (Baird). Color warmer and brighter: coast region 

 north of Eel River, northern California. 



T. b. minor Bailey. Size smaller; color darker: coast region from 

 Cape Mendocino to Cazadero. 



