PROCELLARIN^E. PUFFINUS. THALASSIDROMA. 263 



Procellaria Anglorum, Temm. Man. d'Ornith. ii. 806 ; 

 Puffinus Anglorum, iv. 509. Puffinus Anglorum, Hanks Pe- 

 trel, MacGillivray, Brit. Birds, v. 



318. PUFFINUS OBSCURUS. DUSKY SHEARWATER. 



Bill of the length of the head, little compressed, an inch 

 and a quarter long, light blue, at the end black : tarsus an 

 inch and a half in length, black externally, as are the toes, 

 the webs flesh-coloured ; tail much rounded ; upper parts 

 brownish-black, lower pure white. 



Male, 12, 28, 9, 1 T \, l, 2, ^ 



This species belongs to the southern and tropical regions 

 of the globe, although individuals have sometimes been found 

 far north. 



Procellaria obscura, Gmel. Syst. Nat. i. 559. Procellaria 

 obscura, Lath. Ind. Ornith. ii. 828. Procellaria obscura, 

 Temm. Man. d'Ornith. ii. 808. Puffinus obscurus, Dusky 

 Shearwater, MacGillivray, Brit. Birds, v. 



GENUS CLVII. THALASSIDROMA. PETREL. 



The birds of which this genus is composed are the 

 smallest of those which, being furnished with interdigital 

 membranes, are peculiarly adapted for swimming. They are 

 of slender form, having the body very small, compared with 

 the bulk of plumage with which it is covered ; the neck short 

 and slender ; the head ovate and compressed. Bill shorter 

 than the head, slender, much compressed, decurved at the 

 end, and acute ; upper mandible with the dorsal line at first 

 direct or concave, then abrupt at the end of the nasal tube, 

 afterwards nearly straight for a short space, and finally much 

 decurved, the ridge elevated and separated by grooves from 

 the sides, the edges sharp, approximating toward the end, 

 the tip compressed, decurved, acute ; nostrils dorsal, sub- 

 medial, opening in front by two approximated tubes ; lower 

 mandible with the intercrural space narrow, the lower out- 

 line of the crura decurved, the dorsal line declinate and 

 concave, the edges sharp, close together at the end, the tip 

 compressed and decurved ; mouth of moderate width, dilat- 

 able ; palate convex, with four ridges ; tongue somewhat 

 triangular, much flattened, toward the end horny and point- 

 ed ; oesophagus enlarged below into an enormous proventri- 



