MONOGRAPH OF THE PETRELS. 



b. Smaller ; no white on chin or sides of face, which are 



sooty-black like the rest of the under-surface . . parkinsoni, p. 174 



XIV. — GESTRELATA, Bp. 



Type 



(E. hcesitata 

 (E. leucoptera 

 (E. macroptera 



lessoni, p. 181 



JEstrelata, Bp., Consp. Av., II., p. 188 (1855); Coues, Pr. Acad. 

 Nat. Sci. Philad., 1866, p. 137 



Cookilaria, Bp., Consp. Av., II., p. 190 (1855) . . 



Pterodroma, Bp., Consp. Av., II., p. 191 (1855) 



(Estrelata (nom. emend.), Newton, Ibis, 1870, p. 277; Forbes, Voy. "Challenger," 

 ZooL, IV., pt. XL, p. 39 (1882) ; Salvin, Cat. Birds Brit. Mus., XXV., 

 p. 397 (1896). 



Key to the Species. 



a. Long under tail-coverts white. 



a'. Head white ; hind-neck grey like the back ; 

 a conspicuous black mask in front of and below 

 the eye 



b'. Head black, followed by a white collar, the 

 feathers of which have often dusky tips. 



a". Upper tail-coverts white ; upper-surface 

 brown, the marginal under wing-coverts 

 black, forming a broad band 



b". Upper tail-coverts blackish or slaty-grey ; 

 back bluish-grey ; the black band on the 

 marginal under wing-coverts narrow and 

 interrupted, or practically obsolete. 



a 3 . Marginal coverts of the wing below, 

 black, forming a band round the edge 

 of the wing ; primaries grey below, 

 white only at the base . . 



ft 3 . Margin of the wing below white ; 

 primaries below conspicuously white 

 towards the base 



hcesitata, p. 184 



cervicalis, p. 223 



externa, p. 221 



Head grey or blackish like the back ; or head 

 black, contrasting with the back, but without 

 white collar round the neck. 



XLIV 



