420 CORACITFORMES CHAP. 
grouped together by Nitzsch as Macrochires (long-handed forms) 
from the length of their manual bones, though really the parts 
of the wing nearer the body are proportionally most elongated. 
Swifts certainly differ from Humiming-birds in the broad, flat 
skull, the short curved bill, and the extremely wide gape, besides 
their comparatively sombre coloration ; but these facts cannot be 
allowed to militate against an alliance so strongly confirmed by 
many points of structure, while nothing but the pardonable 
ignorance of former times caused the Family to be united with 
their Passerine analogues, the Swallows. The Cypselidae agree 
with the Zvrochilidae in the number and colour of their eggs, 
and the extraordinarily deep keel of the sternum, which, with 
the long wings, gives so great a power of flight. 
Fam. XI. Cypselidae.—Of this group three Sub-families may 
be recognised, (1) Muacropteryginae, (2) Chaeturinae, and (3) 
Oypselinae. 
The short but robust metatarsi are scutellated anteriorly, the 
scales being nearly obsolete in the Chaeturinae; fairly powerful 
claws terminate the free toes, which are all directed forwards in 
the Cypselinae, though the hallux is somewhat laterally inclined 
in Panyptila, and is said to be occasionally versatile in the 
other Sub-familes. The middle and outer digits in the Cypse- 
linae have the further peculiarity of possessing only three joints, 
while the metatarsi or even the toes are feathered. The ten pri- 
maries, and especially the exterior, are extremely long, with thick 
narrow outer webs; the short secondaries vary from six to eight. 
The square or forked tail has ten rectrices—not uncommonly 
rigid and pointed—as against twelve in Swallows. The furcula 
is U-shaped; the tongue sagittate; the syrinx tracheo-bronchial 
(the muscles not being inserted on the bronchial rings); the 
aftershaft is large or small; the adults have a little blackish 
down on the unfeathered spaces ; the nestlings are blind and naked. 
The coloration is usually greenish-black or mouse- brown, 
occasionally with a white chin, breast, or rump; a rufous collar 
or chestnut ear-coverts occur in Macropteryx and Cypseloides, 
where alone the males differ from the females, and the young 
from both. The Family ranges over the whole world, with the 
exception of the extreme north and south, New Zealand and 
some other islands; the six genera containing about eighty species 
varying in size from about four to fourteen inches. 
