18 ORNITHOLOGICAL EXPLORATIONS. 



G. Lotnviiv, sed rostrum minus et divertissimum, brevins, compressiiiK, 

 niiiivs robustnm, superius magis curvilineum, hasi minus denuda- 



It may uow be asked, what is, then, C. arraf Is it the slender-billed 

 form, equal to californica, and will it have to take the precedence over 

 The latter name ? Pallas says expressly that the tomia at base are not 

 dilated and denuded : "quod non in ArraP 



I was myself ver}' much puzzled by this question, and would proba- 

 bly have answered it in the affirmative had it not been for a specimen 

 which I collected on Berinjj Island. It (No. 92934) is a bird of the 

 year — not much more than six mouths old — and undoubtedly belong- 

 ling to the thick-billed form, as is evident at the first glance, and 

 ^ still more so upon a close comparison with the calif ornica of the same 

 age. From this bird it is clear that the thick-billed species in the first 

 3^ear has the basal part of the tomia feathered and not dilated, the 

 bill being at the same time much shorter and more compressed than in 

 the old birds. Compared with californica of the same age it differs 

 ' especially' in the greater robustness and height of the bill, and espe- 

 cially by the much shorter gonys, the relative length of which is par- 

 ticularly diagnostic of the two species. What confirms my opinion 

 that Pallas's arra is his lomvia, in the first winter, is his expression " su- 

 perius magis curvilineuDt,''^ which will not fit californica in any stage of 

 growth. I therefore think that we are justified in retaining the name 

 ■'•'arra'''' for the thick billed Pacific form. 



Dr. E. Coues was the first author to point out the differences between 

 "the Atlantic and the Pacific forms of the Thick-billed Guillemot (El- 

 Uiott's Aff. Alaska, p. 211 (1875) ), but he did not recognize it as worthy 

 • of a special name until in the second edition of his " Key," where the 

 -Atlantic bird is called Lomvia arra svarbag, and the Pacific simply L. 

 arra, but under the system of nomenclature followed in the " Key" the 

 -Atlantic should have been called Lomvia svarhag and the Pacific 

 Xiomvia svarhag arra, as Pallas's name is later than that given by 

 Briinnich. 



For my own part the inspection of ample material has convinced 

 ■me that the two forms are separable, and even better so than troile and 

 troile californica. 



The "Are"* is extremely abundant at the Commander Islands, and is 



* The Russian name, derived from the voice of the hird, an angry ar-r-r, is origin- 

 ally a])plied to ^7. troile in Europe, and is consequently not specific for the Pacific 

 form which Pallas called C. arra. 



