MONOGRAPH OF THE PETRELS. 



12° 50' N., Long. 107° W. Mr. Lister obtained but one egg at Phoenix Island, and 

 this was found in the interior of a heap of rough coral blocks, piled together by the 

 guano-diggers. It was pure white, of a long oval shape, and measured 2.3 inches in 

 length, and barely 1.5 inch in breadth. Mr. Oates makes the diameter of the same egg 

 1.45 inch {Gat. Eggs Brit. Mus., I., p. 156). 



Mr. Palmer met with this species on Laysan, and also on French Frigate Island 

 (Rothschild, Avif. Laysan, I., p. 45). On the latter he found it breeding, laying its 

 eggs on the ground, and not burrowing like its congeners. The nest, on which both parent 

 birds were often sitting side by side, was composed of a little grass, whereon a single egg 

 was laid. Mr. Rothschild gives the following dimensions : — Axis, 2.24-2.37 inches ; 

 diam., 1.35-1.45. 



Adult male. General colour above sooty-black ; wing-coverts and scapulars like 

 the back ; quills and tail black, the latter slightly brown at the extreme base ; head 

 a little blacker than the rest of the back ; entire under-surface somewhat lighter than 

 the back, and inclining to smoky-brown ; under wing-coverts and axillaries like the 

 breast ; lower greater-coverts and quill-lining with a slight ashy gloss ; bill and feet 

 black (J. J. Lister). Total length 14 inches ; culmen, 1.25 ; wing, 9.8 ; tail, 3.55 ; 

 tarsus, 1.7 ; middle toe and claw, 1.9. 



Adult female. Similar to the male. Total length 13.5 inches ; culmen, 1.3 ; 

 wing, 9.8 ; tail, 3.4 ; tarsus, 1.75 ; middle toe and claw, 2.5. 



A nestling in the Rothschild Collection is covered with sooty down, with a slight 

 reddish tinge on the head, and with the under-surface of the body rather greyer. The 

 series examined by me gives the following measurements : — 



Middle toe 

 and claw. 



2.1 



2.0 



1.9 



2.0 



1.85 



2.5 



1.9 



The wing-measurement varies from 9.5-10 inches, and the tarsus from 1.65-1.8 

 inch, but, as far as one can judge, there is no material difference in the dimensions 

 of the sexes. The tail measures from 3.2 to 3.55 inches. 



The specimen figured is the type kindly lent by the authorities of the U. S. National 

 Museum. The description of the male is that of the Phoenix Island example in the 

 British Museum, and the female is described from a Laysan bird in the Rothschild 

 Collection. 



154 











Wing. 



Tail. 



Culmen. 



TarsuB. 



a. 





Krusenstern Isl. {Mus. Brit.) 



. . 



10.0 



3.35 



1.2 



1.7 



b. 





Do. do. do. 



. . 



9.6 



3.4 



1.15 



1.8 



c. 



S 



Phoenix Isl. do. 



, . 



9.8 



3.55 



1.25 



1.7 



d. 



3 



Laysan Isl. {Mus. Rothschild.) 



. . 



9.5 



3.25 



1.25 



1.75 



e. 



? 



Do. do. 



. . 



9.5 



3.35 



1.2 



1.65 



f- 



s 



Do. do. 



. . 



9.8 



3.4 



1.3 



1.75 



9- 



<? 



Lat. 12° 50' N., Long. 107° W. 



{Mus. 















Rotlischild) 



. . 



9.7 



3.2 



1.3 



1.7 



