ALLEN: AMERICAN COLLARED LEMMINGS. 519 



Cuniculus torquatus Coues, Monogr. N. Amer. Rodentia. Muridae, 1877, . 



p. 246 (part). 

 Dicrostonyx torquatus Miller, N. Amer. fauna, 1896, no. 12, p. 38—40 (part). 

 Dicrosionyx nelsoni Merriam, Proc. Washington acad. sci.. 14 March, 1900, 



2, p. 25. 

 Dicrostonyx hudsonius alascensis Stone, Proc. Acad. nat. sci. Phila., 24 March, 



1900, p. 37. 

 Dicrostonyx hudsonius nelsoni Elliot, Field Columbian mus. publ. Zool. 



ser., 1901, 2, p. 210, fig. 48 (skull and teeth). 

 Dicrostonyx richardsoni Macfarlane, Proc. U. S. N. M., 1905, 28, p. 736 (not 



of Merriam). 



Type. — None specified; the name and description were based by 

 Richardson on notes drawn up by Collie from specimens taken on the 

 American side of Bering Strait, Alaska. 



General characters.— Adults in summer, brilliantly colored, with 

 dark backs, chestnut shoulders and sides, gray cheeks, and an in- 

 distinct black median line from nose to tail; belly whitish, usually 

 washed with ochraceous-buff. Skull with squarely spreading zygo- 

 mata; interparietal nearly rectangular in outline; first and second 

 upper cheek-teeth each with a postero-internal accessory fold of 

 enamel. There is a similar fold antero-internally on the last lower 

 molar, with usually a smaller accessory lobe antero-externally, but 

 this is not always developed, and is lacking in most young skulls. 



Color. — Adult in summer: — sides of the muzzle and an area about 

 the eyes gray, due to a mixture of short hairs some whitish, others 

 black-tipped. Forehead from nose to the nape, black, sometimes 

 grizzled with a few gray hairs. This rtiark is continued as a narrow 

 black median stripe to the root of the tail. Ears marked by a tuft 

 of rusty hairs. Shoulders nearly clear chestnut, about morocco-red 

 of Ridgway (1912) mixed with whitish, this color extending back 

 along the sides of the thorax, and blending dorsally with the grizzled 

 whitish and blackish of the back; hips grayish. Lower surfaces 

 usually washed with orange-buff, but in some specimens whitish. 

 Tail and feet whitish. 



Adult in tvintcr: — pure silvery white, the hairs slaty at their bases. 



Immature in summer: — young animals in first pelage lack the 

 brilliant colors of the adults. The black dorsal stripe runs from the 

 forehead or crown to the tail. The ear-tufts are black; and there is 

 an ill-defined grayish patch below each eye and behind the ear. The 

 rest of the upper parts is a uniform cinnamon-buff, the individual 

 hairs chiefly tipped with ochraceous-bufF, others with minute black 



