174 abstracts: ornithology 



fold and along the east side of the Jackson fault are also favorable; 

 that the best chances for accumulations of oil are probably in the 

 sands above and below the Selma chalk, which lies from 780 to 2700 

 feet below the surface along the crest of the anticline; and finally that 

 there are doubtless other areas of favorable structure in the adjoining 

 region where oil and gas may have accumulated if they are present in 

 commercial quantities anj'where in the region. 



R. W. Stone 



ORNITHOLOGY. —Washington region [April and Maij, 1917]. Harry 

 C. Oberholser. Bird-Lore 19:211-212. 1917. 

 The months of April and May, 1917, were unusually cold at Wash- 

 ington, D. C, and the resultant spring migration of birds was peculiar. 

 Many species of migrants that appeared in April were ahead of their 

 usual schedule, but many that came in Ma}^ were very much delayed. 

 A number of birds rare in the District of Columbia, at least during 

 spring, made their appearance, chieflj^ in May. Conspicuous among 

 these were Phalacrocorax auritus auritus, Larus atricilla, Chlidonias 

 nigra surinamensis, Hydroprogne caspia, Phloeotomus pileatus ahieti- 

 cola, Pisohia fuscicollis, and Protonotaria citrea. H. C. O. 



ORNITHOLOGY. — Description of a n.eiv subspecies of Perisoreus ob- 

 scurus. Harry C. Oberholser. Proc. Biol. Soc. Washington 

 30:185-188. December 1, 1917. 

 A new geographic race of the Oregon jay is here described as Periso- 

 reus ohscurus rathhuni, from Clallam County, Washington. It is 

 darker than either Perisoreus ohscurus ohscurus or Perisoreus ohscurus 

 griseus, and much more grayish above than the former, with a usually 

 broader whitish nuchal collar. Its geographic distribution is appar- 

 ently limited to that part of the State of Washington about Puget 

 Sound and the Strait of Juan de Fuca. H. C. O. 



■♦ 

 ORNITHOLOGY.— A review of the subspecies of the Leach Petrel 



(Oceanodroma leucorhoa iVieiUot). Harry C. Oberholser. 



Proc. U. S. Nat. Mus. 54: 165-172. October 19, 1917. 

 Notwithstanding the considerable attention that has been paid to 

 the petrels of the Oceanodroma leucorhoa group, there is evidently 

 something yet to learn concerning these birds. A study of the entire 

 species, with extensive material, leads to the conclusion that three 

 forms are recognizable: Oceanodroma leucorhoa leucorhoa (Vieillot), 



