228 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 arcticus Linnaeus. 



C. arcticus, Linn. 1735, et auct. Cepphus arct. Pall. 1811. Eudytes arct. 

 Illig. 1811. 



4. Colymbus pacificus Lawrence. 



C. pacijicus, Lawr. Gen. Rep. Birds, 1858, 889. 



Sp. Ch. Generally similar to C. arcticus, but every way smaller ; the wing 

 from an incn 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 lli ; bill 2*12 ; tarsus 2-75." 



Habitat. Northern North America. Pacific coast. 



The types of Mr. Lawrence's C. pacijicus 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 bird is distinct from the 

 European ; or, in other words, that "Colymbus pacijicus Lawr." is the "Colym- 

 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,^ 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. pacijicus 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 pacijicus 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 larclicus; Aichmophorus occidentalis and Clarkii; Podi- 

 h/mbus podiceps and brevirostris, etc. This law seems capable of very extensive 

 application. 



5. Colymbus septentrionalis Linnaeus. 



Colymbus septentrionalis, Linn. 1766, et auct. C. lumme, Brunn. 1764, ad. 

 C. stellatus, Brunn. 1764; Gmel. 1788; Lath. 1790; juv. C. stnatus, 

 Gmel. 1788 ; Lath. 1790 ; juv. C. borealis, Brunn. 1764 ; Gmel. 1788 : 

 Lath. 1790. Cepphus septentrionalis, Pall. 1811. Cepphus stellatus, 

 Pall. 1811. 



[April, 



