164 MR. W. K. PARKER ON STEATORNIS CARIPENSIS. [Apr. 2, 
which the leading modification—the development of the wing—has 
carried with it, in its special varieties, the rest of the body, subjecting 
everything else to its domination, is well seen in the difference be- 
tween Steatornis on the one hand, and the Swifts and Huiming- 
birds on the other. The latter are “ Macrochires ;” their manus is of 
inordinate length and strength, and the Aumerus is very short and 
strong, like that ofa Mole. Butin Steatornis the manus is short, the 
humerus long and slender, and the euditus is extremely long: this bird 
is thus an isomorph in this respect of the aquatic ‘“‘ Longipennes.” 
This great development of the wing, in both cases, has caused a 
peculiar modification from that of the shorter-winged arboreal types, 
viz. the ordinary Passeres, and such Cuculines as the Woodpecker, 
Toucan, and Kingfisher. In all these latter types there is a complete 
bridge over the top part of the interosseous space, formed by one of 
the intercalary metacarpals—that between the normal 2nd and 3rd; 
in the embryo of these types another remnant appears on the ulnar 
side of the 3rd, this is a small 4th metacarpal. 
Now in birds that habitually flit from tree to tree, having only 
wings of moderate size, the remains of the primordial fore paw, not 
wanted in the wing, have a better chance of developing to some 
extent. Thus the remnant of the intercalary metacarpal tused 
with the functional bars is really large in the adults of these 
shorter-winged birds. But in Steatornis, the Cypselidze, and the 
Trochilidze, the great development of the functional bars has aborted 
these archaic, non-functional, parts much more. The same thing 
occurs in other families ; in the terrestrial Gallinaceous types the wing 
is like that of a Sparrow, a Finch, or Crow. In the Swans, 
Geese, Ducks, Gulls, &c., that is in all birds with long and powerful 
wings, the intercalary parts are very small, although nearly always 
demonstrable in the early young or in the embryo. 
The modification of the degs, and with them of the pelvis, follows 
that of the wings and shoulder-girdle ; they are not so much modified 
from a primordial condition as the fore limbs; but they have un- 
dergone, nevertheless, a marvellous amount of change. 
When degeneration of the wings takes place, then the legs be- 
come dominant, as in the Ratitee; that partial descent from a higher 
platform is correlated with an arrest of the brain. 
A very near relationship of Steatornis to the Goatsuckers (Capri- 
mulgide) is rendered somewhat doubtful by the great differences to 
be seen in certain parts of its structure; its skull and dorsal ver- 
tebree are as unlike as can well be. I suspect that the adaptation 
of this type to its nocturnal habits has made it much more like the 
Owls and Fern-Owls than can be accounted for on any theorv of 
descent. If this bird should turn out to be a waif from the ancient 
tribes of the Caprimulgidee, and if Podargus and its allies belong to 
the same group, then the true Schizognathous Goatsuckers (of the 
genus Caprimulgus) must be considered as a culminating family, 
in which the whole skull and face has been lightened and refined 
to a remarkable degree, to give perfection to these crepuscular 
Moth-Hawks. Nitzsch’s term for them, namely ‘Cuculinze noc- 
