PRO CELLARING. PUFFINUS. THALASSIDROMA. 263 
Procellaria Anglorum, Temm. Man. d’Ornith. ii. 806 ; 
Puffinus Anglorum, iv. 509. — Puffinus Anglorum, Manks 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, ly^, 1^, 2, T 3 ^. 
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’Ornifh. ii. 808. — Puffinus obscurus, Dusky 
Shearwater, MacGillivray, Brit. Birds, v. 
GENUS CL VII. 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, deeurved 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 
deeurved, the ridge elevated and separated by grooves from 
the sides, the edges sharp, approximating toward the end, 
the tip compressed, deeurved, 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 deeurved, the dorsal line decimate and 
concave, the edges sharp, close together at the end, the tip 
compressed and deeurved ; 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- 
