13. OCEANODROMA HOMOCHROA (Coues). 



(ASHY PETREL.) 

 (Plate 8.) 



Thalassidroma melania (nee Bp.), Lawr. in Baird, Cassin and Lawr., Birds N. 



Amer., p. 830 (1858). 

 Cymochorea homochroa, Coues, Pr. Acad. Philad., 1864, pp. 72, 77, 91, 114, 116 ; 



Baird, Brewer and Ridgway, Water Birds N. Amer., II., p. 411 (1884). 

 Procellaria homochroa, Gray, Handl. Birds, III., p. 104, No. 10,858 (1871). 

 Oceanodroma homochroa, Ridgway, Pr. U. S. Nat. Mus., VIII., p. 356 (1885) ; Salvin, 



Cat. Birds Brit. Mus., XXV., p. 355 (1896) ; Godman, Biol. Centr.-Amer., 



Aves, III., p. 429 (1904). 



0. melanice similis, sed minor et conspicue schistaceo adumbrata ; plaga 

 alari pallida, magis cinerascente, tectricibus majoribus extus albido fimbriatis : 

 gastrseo toto schistaceo-fuliginoso, tectricibus subalaribus majoribus cinerascenti- 

 albido externe lavatis. 



This is the smallest of the brown-rumped group of the genus Oceanodroma. It is 

 rather more ashy-grey than the other species, and resembles 0. monorhis in general 

 appearance, but is distinguished by its smaller size, and by the hoary-white shade on 

 the greater under wing-coverts. In all the allied species these coverts are smoky -brown 

 without any grey gloss. The bill is shorter and stouter in 0. homochroa. The amount 

 of grey on the under-surface of the body varies somewhat, some birds being blacker 

 than others. The wing-patch is not very distinct, but some specimens have greyish- 

 white edgings to the greater upper wing-coverts. This may be a sign of immaturity. 

 The following are the dimensions of the five specimens examined by me : — 



S Farallon Is. (Mus. Rothschild) 



? Do. do. 



Ad. San Miguel Isl. (Henshaw Coll. : Mus. Brit.) . . 

 <? Point Reyes {Mus. Brit.) . . 

 ? Do. do. 



29 



Wing. 



Tarsus. 



Middle toe 

 and claw. 



5.65 



0.95 



0.95 



5.5 



0.9 



0.9 



5.4 



0.9 



0.9 



5.1 



defective 





5.5 



0.9 



0.9 



