314 



VERTEBRATE ANIMALS OF THE UNITED STATES 



and ponds and streams, in the banks of which they may burrow to form 

 the nest where the young are born. They also form large dome-shaped 

 houses two or three feet high and five or six feet in diameter by heaping 

 up sticks and reeds, the upper portion of which contains a chamber 

 above the level of the water where they spend much of the winter. 

 Their food consists of roots and water-plants, and also shell-fish and 

 other small animals; they raise several litters annually of from 3 to 13 

 each, and do not hibernate, 14 subspecies. 



Subspecies of 0. zihethiciis 



O. z. zihethica (L.). Northeastern and central States; westward to 

 Minnesota and the Great Plains; southward to Georgia and Arkansas, 



except along the Atlantic seaboard south 

 of Delaware Bay. 



O. z. macrodon Merriam. Colors rich 

 and bright; black phase often common; in 

 size the largest of the genus; length 620 

 mm.; tail 274 mm.; hind foot 88: Atlantic 

 coast region from Delaware Bay to 

 Pamlico Sound. 



O. z. osoyoosensis Lord. Color glossy 

 brown to black: Puget Sound region and 

 Rocky Mountains. 



O. z. occipitalis Elliot. Paler and more 

 reddish than F. z. osoyoosensis: northern 

 Willamette Valley and coast of Oregon. 



O. z. mergens Hollister. Color pale; 



size large: northern part of Great Basin. 



O. z. pallida Mearns. Color uniform 



rusty red; size small: Colorado River 



Valley; eastward to Rio Grande. 



O. s. ripensis Bailey. Color light 

 brown; size small: Pecos Valley, Texas. 



0. z. cinnamomina Holl. Color pale, with much red: Great Plains 

 from Manitoba to northern Texas; east to central Iowa. 



O. rivalicia Bangs. Color dark brownish black; length 547 mm.; 

 tail 233 mm.; hind foot 78 mm.: coast region of Louisiana; moults twice 

 annually. 



Family 2. Geomyidae. — Pocket gophers. Thick-bodied rodents 

 with short legs, fore feet fitted for digging, small ears and eyes, and a 

 pair of large fur-lined cheek-pouches which are not connected with the 



Fig. 174. — Incisors of (i) Geo- 

 mys bursarius and (2) Thomomys 

 talpoides {from Merriam). 



