FEOGELLABIID^—PBOCELLABIIN^; PETRELS. 781 



converging to narrow tip 5 less than half as long as head, about half the tarsus. Wings 

 folding beyond tail ; 2d primary longest, 3d little shorter, 1st less than 4th. Tibia briefly 

 bare below; tarsus equal to middle toe and claw; claws compressed, curved, acute. Tail 

 rounded or nearly square, with broad feathers ; under tail-coverts very ample. Several species, 

 distinguished by shape of tail from those of the preceding or following genus. 

 83a. P. pela'gica. (Grr. ireXayixd;, pelagikos, oceanic.) Stokmy Petrel. Above, glossy brown- 

 ish-black, below more fuliginous ; upper tail-coverts white, with blaok tips ; white streaking 

 on crisstim, and usually white touches under the wings. Bill and feet black ; no yellow on 

 webs. Size of the last; wing about 4.50. Common (?) off the Atlantic Coast; not known to 

 breed on our side. This is the rarest of the three little black white-rumped " Mother Carey's 

 chickens " of our Atlantic Coast, easUy distinguished by its short legs and square tail ; Leach's, 

 the most numerous, is also short-legged, but larger and forked-tailed ; Wilson's is interme- 

 ■ diate, with square tail, but very long stilt-like legs, flat claws, and a yellow spot on the webs. 

 327. CYMOCHORE'A. (Grr. *u/»a, kuma, a billow; x°PV''> * dancing.) Sooty Foek-tail 

 Petrels. Bill much shorter than head, about f as long as tarsus, rather stout, as high 

 as or higher than wide at base, the hook strong and acute; nasal tube less than half as long 

 as culmen. Wings moderately long, folding little beyond taU; 2d primary longest; 1st longei 

 than 4th. Tail very long, deeply forked, the feathers all broad, obtusely rounded. Legs 

 short; tibia little bare below; tarsus equal to middle toe and claw, or slightly longer. Of 

 rather large size (for this group) and robust form. Color fuliginous, unicolor or nearly so. 

 Three or four species are known. 



Analysis of Species. 



Upper tail-covertB white. 



General plumage Booty-brown leucorrhoa 823 



No white anywhere. 



Sooty-brown; large; wing 6.75; tail 4.00, forked 1.00 or more melcena 824 



Sooty-gray; small; wing 5.00; tail 3.25, forked about 0.50 homochroa 825 



823. C. leucor'rhoa. {Gr. XevKos, leukos, white; oppos,orhros, ruavp. Fig. 525.) Leach's Petrel. 

 White-rumped Petrel. Coloration as in the last species, with white upper tail-coverts, 

 forming a conspicuous mark; but apt to be lighter — rather 

 of a grayish or even ashy hue on some parts ; but easily 

 recognized, whatever the shade of color. Bill and feet 

 black; iris brown. Length about 8.00; extent 17.50; 

 wing 6.00-6.50; tail 3.00-3.50, forked about 0.75; tarsus 

 1.00; middle toe and claw the same; biU 0.67. N. Am., 

 both coasts, and W. coast of Europe. Abundant on our 

 N. Atlantic coast, breeding from New England northward. 

 Nest in burrows in the ground ; egg single, white. 



824. C. melse'na. (Gr. fieXaiva, melama, black. Fig. 526.) 

 Black Petrel. Form of the last very nearly ; biU more yjo, 535, _Leacb's Petrel, much re- 

 robust ; tarsus a little longer than middle toe and claw. No dnced. (From Tenney, after Audubon.) 

 white anywhere. Plumage sooty brovniish-black, darkest above and on head, more smoky- 

 brown on under parts, grayer on wing-coverts, quite black on wing- and tail-feathers ; biU and 

 feet black ; iris brown. " Length 9.00 ; extent 18.50 ; " wing 6.75 ; tail 4.00, forked 1.20 ; tibia 

 bare 0.50; tarsus 1.25; middle toe and claw 1.10 ; biU 0.60; gape 0.95; height or width at 

 base 0.25 ; nasal tubes 0.80. Cape St. Lucas, L. Gala. ; a rare and little known species. 



825. C. homo'chroa. (G-r. 6n6s, omos, like, equal ; XP°°) ohroa, color.) Somewhat like the last ; 

 smaller, with short, weak, compressed bill, and tarsus no longer than middle toe and claw. 

 No white anywhere. Plumage duU plumbeous or slaty-blackish, more smoky-brownish on 

 lower parts, lighter grayish-brown on greater wing-coverts ; wings and tail black. 2d primary 



