5. OCEANODROMA BEAM, Emerson. 



(BEAL'S STORM-PETREL.) 



Oceanodroma beali, Emerson, Condor, VIII., p. 54 (1906). 



O. leucorrhoa^ similis, sed conspicue minor. 



Mr. W. Otto Emeeson has recently described a form of 0. leucorrhoa from the 

 North Pacific Ocean. The type specimens are a male and female from Sitka Bay, 

 Alaska, in the collection of Mr. J. Grinnell. The measurements are given as follows : — 



S . Wing, 5.90 inches ; tail, 3.10; forking of tail, 0.80 ; tarsus, 0.87. 



P. Wing, 5.75 inches ; tail, 3.10; forking of tail, 0.70 ; tarsus, 0.90. 



These dimensions are certainly rather smaller than those of O. leucorrhoa. A male 

 from Egg Island, Alaska, in the Hon. Walter Rothschild's Museum, has the wing 6.2 inches 

 and a female 5.9, the latter equalling the wing of the male O. beali. Specimens from the 

 islands near Yezo (Memoshiri and Otoke : Mus. Rothschild) have the wing 6.0 — 6.1 

 inches. In the large series of Leach's Petrel in the British Museum, I find that the wing 

 measures from 6.0-6.6 inches in specimens from Western Europe and the Atlantic Ocean ; 

 6.2-6.3 inches in examples from Japan and the Kurile Islands, and 6.1-6.5 inches in 

 those from Eastern North America. 



A specimen in the Rothschild Museum, collected by Mr. Beck in Lat. 5° 30' N., 

 Long. 102° W., has the wing 5.8 inches. If fully grown (which I am inclined to doubt) this 

 may be a specimen of the 0. beali, and represents its southern range, but the other 

 specimens obtained by Mr. Beck in the same latitudes appear to me to be true 0. 

 leucorrhoa, the wing being 6.1 inches in length. 



Mr. Emerson states that 0. beali breeds on the Aleutian and Copper Islands, and 

 on the islets of Sitka Bay, Alaska. Specimens from these localities have hitherto been 

 assigned to 0. leucorrhoa (vide antea). 



It must be remembered that Petrels vary greatly in dimensions, and there 

 is nothing wonderful in the variation in measurements between true 0. leucorrhoa 

 and 0. beali. It is, however, difficult to determine the value of the latter species without 

 seeing specimens from the typical locality ; but I am inclined to doubt the distinctness 

 of 0. beali from 0. leucorrhoa. 



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