BIRDS OF NORTH AND MIDDLE AMERICA. "37 
CEPPHUS MANDTII (Mandt). 
MANDT’'S GUILLEMOT. 
Similar to C. grylle, but greater wing-coverts white to extreme base 
(sometimes with median basal portion dusky), the white wing-patch 
wholly unbroken; size slightly less. 
Adults in breeding plumage (sexes alike).—Uniform fuscous-black 
or very dark fuscous, faintly glossed with greenish, especially on back, 
scapulars, and rump; posterior lesser, middle, and greater wing- 
coverts entirely white, (the feathers all white to extreme base) form- 
ing a large, unbroken, and sharply defined patch on wing; axillars 
and under wing-coverts (except along edge of wing) immaculate white; 
inner webs of primaries extensively white basally, except along shafts; 
bill black; inside of mouth vermilion red; iris dark brown; legs and 
feet vermilion red, the claws blackish. 
Winter plumage.—Wings and tail as in summer; rest of plumage 
pure white, the pileum, back, scapulars, and upper part of rump 
variegated with black, the concealed and part of the exposed portion 
of the feathers being black; legs and feet paler red. 
Young.—Similar to the winter plumage, but white wing-patch 
broken by blackish tips to the feathers (their concealed bases white, 
however), the secondaries and primary coverts with white terminal 
spots, the rump and under parts indistinctly barred with grayish 
dusky, and pileum with much less of black. 
Downy young.—Plain sooty blackish or dark fuscous, paler and 
more grayish on under parts. 
Adult male.—Wing, 150.5-165 (158.1); tail, 40.5-51 (47.7); exposed 
culmen, 28-33 (29.6); tarsus, 29-32 (30.6); middle toe, 33-38 (35.2).¢ 
Adult female.—Wing, 149-156.5 (153.1); tail, 44-51 (47.5); ex- 
posed culmen, 28-31 (29.7); tarsus, 28-30 (29.4); middle toe, 33- 
35.5 (34.2).° 
@ Hight specimens. 6 Four specimens. 
Ex- . 
Locatity. Wing. | Tail. | posed | Tarsus. Meals 
culmen. Oe 
; MALES. 
One adult male from Siberia (Cape Bolshaja)......-......-.--- 152.5 50 30 30 34.5 
One adult male from Spitzbergen.............2..2.-.2.-2---0-- 161 47.5 30 29 33 
Six adult males from eastern North America (Greenland to 
Massa Chtsetts): cayiec miss awnticiromsteuiersiemiaineined sicigeie anecineres 158. 6 47.3 29. 4 31 35.7 
FEMALES. 
One adult female from Spitzbergen..............-222220eeeee ee 156.5] 46.5) 31 30 35.5 
One adult female from Ungava.............2.--2-022ee eee eee 153 48.5 28 30 33 
One adult female from Newfoundland .................-.-..--- 149 44 30 28 33.5 
One adult female from northern Alaska (Point Barrow)....... 154. 5 51 ere "99.5 35 
40017—19—Bull. 50, pt 8——48 
