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PROCEEDINGS OF THE ACADEMY OF 
the species is from Russian America. The large series which the Smithsonian 
possesses, were collected in the vicinity of Great Slave Lake and McKenzie’s 
River, by R. Kennicott and B. R. Ross, Esqrs. It has not been obtained from 
the Atlantic coast. 
3. Colymbus aecticus Linnaeus. 
C. arcticus, Linn. 1735, et auct. Cepphus arct. Pall. 1811. Eudytes arct. 
Illig. 1811. 
4. Colymbijs pacificus Lawrence. 
C. pacificus , Lawr. Gen. Rep. Birds, 1858, 889. 
Sp. Ch. Generally similar to C. arcticus . but every way smaller ; the wing 
from an inch to two inches shorter, the legs and feet proportionately shorter, 
and the bill smaller, shorter, weaker, usually with a less decurved culmen, 
and more acute tip. Colors precisely as in C. arcticus. “Length 25 inches ; 
wing 11^ ; bill 2'12 ; tarsus 2*75.” 
Habitat. Northern North America. Pacific coast. 
The types of Mr. Lawrence’s C. pacificus are young birds, and their relation- 
ship can only be determined by their size and form. A comparison of these 
types with an extensive series of skins of the adult bird, from the interior 
of Northern North America, has shown them to be beyond a doubt identical. 
The entire series differs from a fine adult European bird furnished for examina- 
tion by the Copenhagen Museum, in those points which are given in the diag- 
nosis. The difference is very marked indeed, and while all the birds in the 
North American series agree perfectly with each other, there is, at the same 
time, not the slightest graduation between them and the European bird. This 
would seem to indicate that the North American bircl is distinct from the 
European ; or, in other words, that “ Colymbus pacificus Lawr.” is the “ Colyrn - 
bus arcticus ex America .” Upon this supposition it would be necessary to 
exclude the C. arcticus from our avi-fauna. There is in the collection, how- 
ever, a specimen (from Puget Sound) which is fully as large as the European 
bird, with which it agrees in the minutest particulars, and is much larger and 
stouter every way than the rest of the series. I have, therefore, at present 
no other alternative than to admit the C. pacificus as distinct from the arcti- 
cus, in view of the differences constantly observable, and at the same time to 
retain the latter as an inhabitant of North America. I think it probable, 
however, that if the true arcticus is really found in North America, it is rather 
as an infrequent visiter than as a permanent resident. I do not regard the 
question as yet definitely settled, especially as the single European skin 
examined may have been an unusually large specimen. Further investigation 
will be necessary to definitely settle the point. 
Should the pacificus prove to be really distinct from the arcticus , it would 
be another example of a peculiar law which prevails extensively throughout 
the Colymbidce and Podicipidce. This is, that nearly all the species have, so 
to speak, their analogues, agreeing in colors and general appearance, but dif- 
fering in size, and in the size, shape, and stoutness of the bill. Instances are 
seen in the cases of Colymbus Adamsii and torquatus ; Podiceps grisiegena and 
Holbolli; P. cornutus and ? arcticus; Aichmophorus occidentalis and ClarJcii; Podi- 
lymbus podiceps and brevirostris, etc. This law seems capable of very extensive 
application. 
5. Colymbus septenteionalis Linnaeus. 
Colymbus septentrionalis , Linn. 1766, et auct. C. lumme, Briinn. 1764, ad. 
C. stellatus, Briinn. 1764; Gmel. 1788; Lath. 1790; juv. C. striatus, 
Gmel. 1788 ; Lath. 1790; juv. C. borealis , Briinn. 1764; Gmel. 1788; 
Lath. 1790. Cepphus septentrionalis , Pall. 1811. Cepphus stellatus , 
Pall. 1811. 
[April, 
