562 NORTH AMERICAN BIRDS. 



(3.20), depth of bill at nostrils 1.05-1.10 (1.08), tarsus 2.60-2.85 

 (2.75). Hub. Commander Islands, Kamtschatka. (Probably 

 also westernmost Aleutians.) 



C. corax behringianus Dybowski. Bering's Raven.^ 



6^ Feathers of neck, all round, pure white at base ; nasal tufts covering much 



more than basal half of upper mandible ; exposed culmen less than 2.40, 



wing less than 15.00. 



Length 18.75-21.00, wing 13.10-14.25 (13.67), tail 7.50-8.G0 (8.10), 



exposed culmen 2.00-2.35 (2.15), depth of bill at base .85-.90 (.87), 



tarsus 2.20-2.50 (2.35). Eggs 1.74 X 1-21, with markings averaging 



finer and more longitudinal than in other 8j)ecies. Hah. Southwestern 



United States and table-lauds of Mexico; north to Indian Territory, 



Kansas, Colorado, and southern California, south to Guanajuato and 



Puebla 487. C. cryptoleucus Couch. "White-necked Raven. 



a}. Feathers of throat short, blended. (Crows.) (Nest usually in trees.) 



b^. Nostrils completely hidden by the fully-developed nasal tufts ; corner of 

 mouth feathered. 

 c^. Tarsus 2.15, or more; lower parts glossed with violet (on margins of 

 feathers) like upper parts; wing averaging more than 11.75, tail 

 averaging more 1jian 7.00. 

 d}. Larger, with relatively larger and thicker bill. 



e^ Wing and tail averaging longer, but bill and feet decidedly 

 smaller; length 17.00-21.00, wing 11.90-13.25 (12.36), tail 

 6.90-8.00 (7.43), exposed culmen 1.80-2.05 (1.92), depth of 

 bill at base .72-.82 (.76), tarsus 2.20-2.40 (2.27). Eggs 1.69 

 X 1-17- Hab. Eastern North America, except southern 

 Florida and arctic districts. 



488. C. americanus Aud. American Crow. 



e^. Wing and tail averaging shorter, but bill and feet decidedly 



larger; length about 20.00, wing 11.50-12.30 (12.15), tail 



7.00-7.70 (7.23), exposed culmen "2.00-2.20 (2.08), depth of 



bill at base .75-.85 (.80), tarsus 2.40-2.50 (2.45). Hab. 



Southern Florida. 



488^. C. americanus jBoridanus Baird. Florida Crow. 



cF. Smaller, with relatively smaller and more slender bill. 



Length about 18.50-19.25, wing 11.10-12.75 (11.95), tail 6.45- 

 7.80 (7.10), exposed culmen 1.60-1.95 (1.78), depth of bill 

 at base .62-.70 (.68), tarsus 2.15-2.40 (2.23). Hab. Western 

 United States, north to Washington Territory (Puget 

 Sound), Idaho, Montana, etc., south to northern Mexico, 

 east to Eock}^ Mountains. 



— . C. americanus hesperis Eidgw. California Crow.' 



1 Corvu8 corax hehringiaiins Dybowsk. Bull. Soc. Zool. France, 1883, 363. 



2 New subspecies ; a very strongly characterized race which also differs markedly in habits and notes from 

 the eastern bird. 



