890 
U. S. P. E. E. EXP. AND SURVEYS — ZOOLOGY GENERAL EEPORT 
an examination of specimens of G. arcticus, in the Museum of the Phil. Acad., I found a fully 
adult individual ; also one approaching maturity. These were precisely alike as regarded the 
form of their hills ; there was also a specimen of a young bird labelled " G. arcticus, 7 ' but, 
having no locality marked upon it, it came with the Kivoli collection, and was originally from 
that of the Duchess de Berri ; the bill was weak and slender compared with the two other spe- 
cimens, and the whole appearance of the bird cpuite different. I could not, therefore, reconcile 
them as being the same ; the young specimen in the Phil. Acad, was exactly like the species 
now described, and may have come from the Pacific. 
Bichardson Fauna Bor. Am., vol. II, p. 475, describes the young of "C. arcticus," as "closely 
resembling those of 1 G. glacialis,' but may be distinguished by their inferior size, a slight 
curvature of the upper mandible, and the want of a groove on the under one, which is not 
thickened in the middle." 
The above described specimens bear very little resemblance to " G. glacialis," which strengthens 
my opinion in thinking them distinct from G. arcticus. The true position of the Pacific species 
can only be surely settled by obtaining it in adult plumage. 
Catal. No. 
Locality. 
Whence obtained. 
Length. 
Wing. 
9921 
9924 
San Diego, Cal 
Lieut. Trowbridge 
Dr. Suckley 
24. 00 
25.00 
10. 25 
11. 25 
COLYMBUS SEPTENTBIONALIS, Linn. 
The Red-throated Diver. 
Colymbus septentrionalis, Linn. S. N. I, 1766, 220.— Bonap. Syn. 1828, 370.— Rich, and Sw. F. B. A. II, 1831, 476.— 
Nutt. Man. II, 1834, 519.— Aud. Orn. Biog. Ill, 1833, 20: V, 1839, 625.— Ib Birds Am. 
VII, 1844, 299 ; pi. cccclxxviii. 
Colymbus lumme, Bkunn. Orn. Bor. 1764, 132. 
Colymbus stellatus, Brunn. Orn. Bor. 1764, 130. 
Colymbus striatus, Gm. I, J788, 556 (young.) 
Colymbus borealis, Lath. Ind. Orn. II, 1790, 802 (young.) 
g P . Ch, — Adult. Front, sides of the head, upper part of the throat, and sides of the neck, clear bluish gray ; upper part of the 
head of the same color, intermixed with blackish spots; the hind neck streaked longitudinally witli white on a greenish black 
ground, the white feathers being raised above the others. On the fore part of the neck is a large longitudinal patch of deep 
reddish brown. Upper plumage brownish black, slightly tinged with green, and on the upper part of the back and lower part 
and sides of the neck streaked and mottled with white. Wings and tail brownish black ; under plumage pure white, with a baud 
across the hind part of the abdomen, and the lower tail coverts brownish gray ; bill bluish black ; iris bright red ; tarsi and feet 
brownish black externally, on the inside pale flesh color; claws yellowish at the base, dusky at the end. 
Length, 27 inches ; wing, 1 1£ ; tail, 2 h ; bill, 24, ; tarsus, 2 J. 
Youny. Upper part of the head and hind neck dull gray, streaked with grayish white ; back and wings blackish gray, pro- 
fusely marked with oval shaped white spots, there being two ou each feather, smallest on the upper part of the back and largest 
on the tertiaries ; quill feathers and tail blackish brown, the latter edged with white ; sides of the neck white, speckled minutely 
with gray ; under plumage silky white, crossed on the lower part of the abdomen by a dusky band ; bill bluish gray, dusky on 
the ridge and flesh colored at the base. 
Hub. — During the winter as far south as Maryland ; inhabits as far north as the Arctic seas ; found also on the Pacific coast. 
Two specimens are in the collection from the western side of the continent, and present no 
marked differences from those of the Atlantic coast. No. 9923 is in the anomalous dress of an 
