BIRDS OF NORTH AND MIDDLE AMERICA. 733 
KEY TO THE SPECIES OF CEPPHUS. 
t. Smaller (exposed culmen less than 35, tarsus not more than 35 mm.). 
6. Under wing-coverts pure white; rectrices 12. 
c. Greater wing-coverts with at least their basal half black, this often showing as 
a narrow band beyond tipsof middle coverts. (Coasts of northern Europe 
and eastern North America, from southern Greenland to Labrador, south, in 
winter to New Jersey, etc.)..-.......--22----22--- Cepphus grylle (p. 733). 
ec. Greater wing-coverts white to extreme base (sometimes a little dusky 
along concealed median basal portion). (Coasts and islands of Arctic 
Ocean and northern Atlantic Ocean, breeding southward to Hudson Bay 
and coast of Labrador; in winter south to New Jersey and Norton Sound, 
Mla kis) iin swe wees seem ewer careers Cepphus mandtii (p. 737). 
bb. Under wing-coverts light brownish gray; rectrices 14. 
c. Greater wing-coverts broadly tipped with white, the white on middle and 
posterior lesser coverts forming a conspicuous patch, separated into two only 
on distal coverts. (Coasts and islands of northern Pacific Ocean, south to 
California and Japan.)............------2------ Cepphus columba (p. 740). 
ce. Greater wing-coverts very narrowly (if at all) tipped with white; the white on 
middle and posterior lesser coverts (if present) forming three entirely sepa- 
rated bands. (Sometimes no white at all on wings.) (Kuril Islands to 
southern Kamchatka and northern Japan.)..Cepphus snowi (extralimital).¢ 
aa, Larger (exposed culmen not less than 41.9, tarsus not less than 35.6). (No white 
on wings). 
b. No white on head (color entirely sooty or blackish). (Greenland, Iceland, etc.) 
Cepphus motzfeldi (p. 742). 
bb. A whitish orbital and postocular area. (Coasts and islands of northeastern Asia, 
from northern Japan to Sea of Okotsk and Commander Islands, Kamchatka; 
occasional or accidental on Aleutian Islands?)......- Cepphus carbo (p. 743). 
CEPPHUS GRYLLE (Linneus). 
BLACK GUILLEMOT. 
Adults in summer ° (sexes alike).—Plain fuscous-black or very dark 
fuscous, faintly glossed with greenish, especially on back, scapulars, 
and rump; posterior lesser, middle, and distal half of greater wing- 
coverts immaculate white, forming a large patch on the wing, some- 
times superficially uninterrupted but usually broken by exposure of 
the black of basal portion of greater coverts, which also have the 
greater part of inner webs black; axillars and under wing-coverts, 
except along edge of wing, immaculate white; bill black; inside of 
mouth vermilion red; iris dark brown; legs and feet vermilion red 
(in life), the claws blackish. 
Winter plumage.—Wings and tail only as in summer; rest of plum- 
age pure white, the pileum, back, scapulars, and upper part of rump 
' @Cepphus snowi Stejneger, Auk, xiv, April, 1897, 201 (Raikoka Island, Kuril group, 
Japan; coll, U. 8. Nat. Mus.); Proc. U. 8. Nat. Mus., xxi, 1898, 272 (Kuril Islands); 
Clark (A. H.), Proc. U. 8. Nat. Mus., xxxviii, 1910, 33 (Cape Lopatka, Kamchatka; 
Kurli Islands; n. end of Yezo, Japan); Oberholser, Auk, xxxiv, 1917, 191 (record in 
Niedieck’s Kreuzfahrten im Bering meer, 1907, 250, for Kenai River, Alaska, probably 
not valid).— Uria snowi Grant, Cat. Birds, Brit. Mus., xxvi, 1898, 588 (Kuril Islands ; 
Petropaulski, Kamchatka).—{Pseuduria] snowi Sharpe, Hand-tist, i, 1899, 131. 
b This plumage is sometimes carried through the winter, perhaps by very old birds 
