72 NORTH AMERICAN BIRDS. 
a. Belly entirely white. 
b». Throat and collar round hind-neck white ; length 8.75-9.00 ; tail emarginated 
for about .75; tarsus 1.65-1.75, middle toe, with claw, 1.25, or more. 
Hab. Intertropical seas. 
C. tropica (GOULD). Tropical Petrel.! 
b%. Throat usually with only concealed white, and without white on hind-neck ; 
length 7.50-8.00, wing 6.00-6.50, tail 3.00-3.30, even; tarsus 1.40-1.60, 
middle toe, with claw, 1.05-1.10. Hab. Intertropical seas, north, 
casually, to coast of Florida. 
110. C. grailaria (ViEILL.). White-bellied Petrel. 
a’, Middle line of belly dusky. 
No white on hind-neck, but throat sometimes white, and feathers of 
forehead white beneath surface; dusky of belly usually connected with 
that on chest; length 8.50-8.75; tail usually emarginated for about .75; 
wing 6.25-6.75, tarsus 1.60-1.70, middle toe, with claw, 1.05-1.15. Hab. 
South Pacific. 
C. melanogaster (GOULD). Black-bellied Storm Petrel. 
Genus PELAGODROMA ReicuensacH. (Page 56, pl. XV., fig. 2.) 
Species. 
Forehead, superciliary stripe, and lower parts, pure white; top of head, broad 
stripe behind eye, and upper parts generally, slate-color, sometimes inclining to 
plumbeous; upper tail-coverts light ash-gray; quills and tail-feathers blackish ; 
bill black ; tarsi deep black ; feet black, the webs mostly yellowish ; wing 5.90-6.40, 
tail 2.90-3.30 (forked for .25-.35), tarsis 1.52-1.70, middle toe, with claw, 1.37-1.40. 
Had. Southern seas, accidental off coast of Massachusetts. 
111. P. marina (Lars.). White-faced Petrel. 
1 Thalassidroma tropica GouLp, P. Z. 8. 1837, 366. 
2 Thalassidroma mel a GouLp, Ann. Mag. N. H. xiii. 1844, 367; B. Austr. vii. 1848, pl. 62. 
dg 
