332 PYGOPODES, DIVING BIRDS. 
24. North Atlantic, abundant; S. at least to Carolina (Cowes). A special 
state of P. major? SrrickLanp, Proc. Zool. Soc. 1832, 129; DrKay, 
New York Birds, 287, pl. 136, f. 298; Lawr. in Bp., 834; Cougs, 
Proc. Phila. Acad. 1864, 
123. . ‘¥ULIGINOSUS. 
Dark-bodied Shear- 
water. Similar to the 
last; feet flesh color, 
slightly obscured out- 
side; lining of wings 
. mostly white ; smaller; 
FG. 212. Sooty Shearwater. wing 11, etc. Cape St. 
Lucas. Very doubtful. I allow this, and several others, to stand, because 
it is still uncertain what reduction of the species of this genus will prove 
necessary. Vectris amaurosoma Cours, 1. c. 124. . . . AMAUROSOMA. 
Slender-billed Shearwater. Plumage as in the foregoing; size less; tail 
shorter; bill smaller. Bill dusky-greenish, with yellow; feet yellowish, 
blackish behind and under the webs. Length about 14; wing 10; tail 
34, graduated an inch; bill 14; tarsus under 2; middle toe and claw 2%. 
N. Pacific Coast. Trmm., Planches Color. No. 587; Trem. and Scutu., Fn. 
Japon. 131, pl. 86; Bonar., Consp. Av. ii, 202; Couns, /. c. 126; Barren, 
Trans. Chicago Acad. i, 1869, 322, a 34, f. 2. PP. tristis, curilicus and 
brevicauda of authors? . . . . SUT eee Soe SP eLENUIROSPRISS 
Order PYGOPODES. Diving Birds. 
In the birds of this order the natatorial plan reaches its highest development. 
All the species swim and dive with perfect ease; many are capable of remaining 
long submerged, and of traversing great distances under water, progress being 
effected by the wings as well as by the feet. Few other birds, such as cormorants 
and anhingas, resemble the Pygopodes in this respect. The legs are so completely 
posterior, that in standing the horizontal position of the axis of the body is impos- 
sible; the birds rest upright or nearly so, the whole tarsus being often applied to 
the ground, while the tail affords additional support ; progression on land is awkward 
and constrained, only accomplished, in most cases, with a shuffling motion, when 
the belly partly trails on the ground. The penguins, and one species of auk, cannot 
fly —the former, because the wings are reduced to mere flippers with scaly feathers, 
the latter because the wings, although perfectly formed, are too small to support 
the body. The rest of the order fly swiftly and vigorously, with continuous wing- 
beats. The rostrum varies in shape with the genera; but it is never extensively 
membranous, nor lamellate, nor furnished with a pouch. The nostrils vary, but are 
neither tubular nor abortive. The wings are short, never reaching when folded to the 
end of the tail, and often not to its base. The tail is short, never of peculiar shape, 
generally of many feathers; there are, however, no perfect rectrices in the grebes. 
The crura are almost completely buried, and feathered nearly or quite to the heel. 
The tarsus is usually compressed, sometimes, as in the loons, extremely so; in the 
penguins, on the contrary, it is much broader across than in the opposite direction, 
being nearly as wide as long. The front toes are completely palmate in the loons, 
