BIRDS—CYPSELIDAE—PANYPTILA MELANOLEUCA. 141 
the tarsus is naked. The greatest difference is in the hind toe, which, instead of being slender 
and entirely anterior like the rest, is lateral, and very short and thick. The tail feathers are 
much more rigid, the fork not so deep, the outer feather equal to, or a little shorter than, the 
second, instead of being considerably longer. The second quill is longest in both. The bills 
of both are quite similar. 
The feathered legs readily distinguish the genus from the other American swifts. 
There appears to be a tendency on the inner toe to a more naked condition than in the others. 
According to Burmeister, the numerical proportion of the joints of the anterior toes in this 
genus is the same as in most birds, namely, 3, 4, 5, instead of 3, 3, 3. This statement I have 
not yet been able to veri‘y in the case of the North American species. 
The South American species of this genus, as P. cayanensis, appear to be slenderer in form 
than P. melanoleuca, and the tail more deeply forked, approaching in this respect to Hirwndo 
rufa. The feet, however, are very similar. 
PANYPTILA MELANOLEUCA, Baird. 
White-throated Swift. 
Cypselus melanoleucus, Bairp, Pr. A. N. Sc. Phil. VII, June, 1854,118. (San Francisco mountains, N. M.)— 
Cassin, Illust. I, 1855, 248. 
Sp. Cu.—Wings very long ; tail forked ; tarsi and feet covered with feathers. Black all over, except the chin, throat, middle 
of the belly as far as the vent, a patch on each side of the rump, the edge of the outer primary, and blotches on the inner webs 
of the median tail feathers, near the base, which are white, as is also a band across the ends of the secondaries. Length 5.50 ; 
wing 5.50; tail 2.70. 
Hab.—Colorado Basin, New Mexico. 
The bill of this species is very small and short, though deep and much curved from the base. 
In shape and size it is somewhat similar to that of Chaetura pelasgia. The wings are very long 
and falcate, extending more than an inch beyond the tail. This excessive development is, 
however, almost entirely in the primaries, which measure nearly four times the secondaries, 
starting at the carpal joint. The second quill is longest, the first intermediate between this 
and the third ; the remaining primaries decrease rapidly to the last, are elongated acute, with 
the points but little rounded. The tail is composed of ten feathers; it is acutely and quite 
deeply forked, the feathers all lanceolate acute, with much stiffer shafts than in the swallows. 
The outer feather is a very little shorter than the second, which islongest. The greatest depth 
of the fork is about half an inch. 
The tarsi and toes are very thick and strong, though short. The anterior faces of both are 
covered with broad black feathers. The toes are much united anteriorly, The claws are all 
thick and much curved. 
The prevailing color of the upper parts is of a sooty black, darker than in Chaetura pelasgia ; 
the head is brownish, however, and almost exactly as in the last mentioned species. The whole 
under parts as far as the breast, and a median line extending to the arms, are white, as is also 
a patch on each side of the rump, mostly concealed by the wings. The remaining under parts, 
including the lower coverts, are black like the back. The tail feathers, except the outer, have 
an elongated and obscure spot of whitish on the inner web near the base, otherwise they are in 
color like the back. The quills are rather more brown. The ends of the secondary quills are 
white, forming a conspicuous transverse band. The outer web of the outer primary is also 
narrowly edged with white. 
