A REVIEW OF THE SUBSPECIES OF THE LEACH PETREL, 

 OCEANODROMA LEUCORHOA (VIEILLOT). 



By Harry C. Oberholser, 



Of the Biological Survey, United States Department of Agriculture. 



Notwithstanding the considerable attention that has been paid to 

 the petrels of the Oceanodroma leucorhoa group, the last word has 

 evidently not yet been said on the subject. Nor do we consider 

 that all points in this difficult case are settled by the present investi- 

 gation, which we undertook in connection with the identification of 

 the specimens of this species in the Biological Survey collection; but 

 the following notes on the status of the different forms of Oceanodroma 

 leucorhoa seem worthy of presentation in print while we are waiting 

 for more material to clear up the remaining uncertainty concerning 

 their geographic distribution. 



The latest author to discuss the relationships of these birds i 

 recognized two forms — Oceanodroma leucorhoa leucorhoa from the 

 Atlantic Ocean, Bering Sea, and the Aleutian Islands, and Oceano- 

 droma leucorhoa Tcaedingi from the Pacific coast of North America 

 from southern Alaska southward. This conclusion, however, was 

 arrived at apparently without examination of the type series of 

 Oceanodroma leucorhoa Icaedingi. 



For the present comparisons we have had available the collections 

 of the United States National Museum, including that of the Biological 

 Survey of the Department of Agriculture, and also that of the Carnegie 

 Museum, for which last the writer's thanks are due Mr. W. E. C. 

 Todd. This material comprises altogether 158 specimens, repre- 

 senting nearly all parts of the North American range of the species, 

 and includes the type series of Oceanodroma Jcaedingi Anthony, 

 with, of course, the type, and also the types of Oceanodroma heali 

 Emerson and Oceanodroma heldingi Emerson. All measurements 

 have been taken in millimeters, and otherwise as in the writer's 

 paper on Butorides virescens.^ 



We are able to recognize three forms of Oceanodroma leucorhoa, as 

 set forth below : 



OCEANODROMA LEUCORHOA LEUCORHOA (Vieillot). 



Frocellaria leucorhoa Vieillot, Nouv. Diet. d'Hist. Nat., vol. 25, 1817, p. 422 



(maritime parts of Picardy, France). 

 Frocellaria leachii Temminck, Man. d'Ornith., ed. 2, vol. 2, 1820, p. 812 (St. Kilda 



Island, Scotland). 



1 Willett, Auk, vol. 32, July, 1915, p. 301. 



2 See Proc. U. S. Nat. Mus., vol. 42, Aug. 29, 1912, p. .533. 



Proceedings U. S. National Museum, Vol. 54— No. 2230. 



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