70 NORTH AMERICAN BIRDS. 
a', Longer upper tail-coverts broadly tipped with black; under side of wing with 
more or less of white; tail even, or slightly rounded ; length §.50-5.75, wing 
4.50-4.90, tail 2.40-2.60, culmen .40-.50, tarsus .90, middle toe .60-.65. Ligg 
1.09 x .83. Hab. North Atlantic, south to Newfoundland Banks and 
western coast of Africa........ereeee 104. P. pelagica Linn. Storm Petrel. 
a’, Longer upper tail-coverts entirely white; no white on under side of wing ; tail 
emarginated; wing 5.20, tail 2.40, the middle feathers .20 shorter; tarsus .85, 
middle toe (with claw) .70. Hab. Vicinity of the Galapagos Islands. 
P. tethys Bonar. Galapagos Storm Petrel.! 
Gzunus OCEANODROMA Rercuunpacu. (Page 56, pl. XVIL, figs. 1, 2.) 
Species. 
Common CHaracters.—Above dusky or grayish, with or without white on 
upper tail-coverts; lower parts uniform bluish gray or sooty, or white interrupted 
by a grayish band across chest. 
a!, No white on upper tail-coverts. 
b'. A white collar round hind-neck. 
Lower parts white, with a grayish collar across chest; upper parts 
grayish, the quills blackish, the forehead and sides of head white; 
length about 8.25, wing ——?, tail 3.75, tarsus 1.00. Hab. North 
Pacific (“ Northwest coast of America’). 
—.O.hornbyi (Gray). Hornby’s Petrel. 
0%. No white collar round hind-neck. 
ce! Color bluish gray, above and below. 
Uniform bluish gray, fading to white on chin, throat, and under 
tail-coverts; orbital region, longer scapulars, innermost wing- 
coverts, anterior and outer lesser wing-coverts, together with 
quills, dusky; other lesser coverts, middle and greater coverts, 
and tertials, broadly edged with ashy white ; length 8.00-9.20, 
wing 5.90-6.40, tail 3.75-4.00 (forked for about 1.00). Egg 1.37 
X 1.03. Hab. North Pacific, south on the American side to 
Oregon............. 105. O. furcata (GmEL.). Fork-tailed Petrel. 
ce. Color sooty brownish or dusky, above and below. 
d', Wing more than 6.50; tarsus 1.00, or more. 
é', Sooty blackish, lighter and browner beneath, the greater wing- 
coverts and outer webs of tertials light grayish brown; 
wing 6.80, tail 3.90 (forked for about 1.20), tarsus 1.20. 
Hab. Coast of Mexico, north to Lower California. 
107. O. melania (Bonap.). Black Petrel. 
e. Sooty slate-color, the head, including throat, appreciably paler 
and more plumbeous; greater wing-coverts light grayish; 
1 Procellaria tethys Bonap., Comp. Rend. xxxviii. 1854, 662; Consp. ii. 1857,197. Sanv. Trans. Zool. Soc. 
Lond. ix. pt. ix. 1875, 507, pl. 88, fig. 2. 
