VOl 'l906 ni ] Beklkpsch, Description of a New Petrel. 185 



ON A NEW FORM OF OCEANODROMA INHABITING 



SAN BENITO ISLAND, OFF THE COAST OF 



LOWER CALIFORNIA. 



15Y HANS GRAF VON BERLEPSCH. 



Oceanodroma monorhis chapmani Berl. 



0. O. monorhis dictse valde affinis sed alis multo, cauda tarsisque paulo 

 brevioribus, rostro longiore, necnon corpore supra nigrescentiore, minus 

 griseo lavato, distinguenda. 



Al. 149-147 caud. 77-76 culm. 28f-28^ tars. 22J-22 mm. 

 Habitat in insula San Benito dicta, maris pacifici California inferior! 

 proxima. 



Typus in Mus. H. v. B. (tf San Benito Isld.). 



In the year 1899 I received through Mr. H. W. Marsden of 

 Clifton, Bristol, a number of rare North American birds, which 

 he had to sell in commission for Mr. C. K. Worthen of Warsaw, 

 111., whose firm name is to be found printed on the labels. From 

 this consignment I picked out several specimens of Petrels be- 

 longing to the genus Oceanodroma, collected in the San Benito 

 and Guadelupe Islands off the coast of Lower California. They 

 bear labels in a handwriting I do not know. These Oceanodroma 

 are evidently referable to three different species, viz.: 



1. 0. macrodactyla W. E. Bryant from Guadelupe Island, a 

 large species with partly white upper tail coverts. 



2. 0. melania (Bp.) from San Benito Island, a large species of 

 nearly uniform blackish coloration, but with whitish brown apical 

 borders to the upper wing coverts. Erroneously labelled as 0. 

 socorroensis. 



3. A species evidently closely allied to 0. monorhis (Swinh.), 

 but erroneously labelled as "0. melania." From the latter the 

 two specimens from San Benito Island now in my collection 

 differ in their much smaller size and in having the front, face and 

 chin suffused with grayish slate color instead of being uniform 

 with the rest of the body, also in the back being paler and of a 

 more brownish black. Otherwise the coloration in these two 

 birds is the same as in O. melania. 



