SYSTEMATIC POSITION OF THE SWIFTS. 93 
obtain this coveted power, and to forego development in their hind 
limbs, that their fore limbs might carry them more swiftly by far 
than any of their relatives, ‘“‘ through the great deserts of the air,” 
as Calderon expresses it. I do verily believe that this is the key 
to the secret—that their large wings have materially detracted 
from their puny legs. 
In matters of this sort I never differ from my friend Dr. 
Sclater without a strong feeling of misgiving ; and yet his expres- 
sion, that ‘the Swifts have no relationship whatever with the 
Swallows, Hirundinide” (Proc. Zool. Soc., 1865, p. 593), is, I 
consider, too emphatic to be true. 
It would not be true of the relationship of the Swifts to any 
Passerine bird; for they certainly lie on the Passerine border of 
the Picarie, if they cannot be put even as abnormal Coraco- 
“morphe. 
I agree with my friend Dr. Shufeldt that the “ Swallow and 
the Swift are near akin.” My own opinion is not the simple 
judgment it was forty years ago. I have observed a good many 
things since then in the structure of birds of all sorts. 
To take one fact,—all the Passerine birds are ‘‘ Finch-jawed”’ 
(Aigithognathous) ; no other birds but the Swifts are so, except in 
an imperfect degree. This peculiar structure, which is isomorphic 
with what is found among the Mammalia, very commonly, and 
which arises from a fusion of the vomer (or vomers) with the 
floor of the nasal labyrinth (base of “ middle turbinal” of man), 
is not the only thing in which the Swifts agree with the 
Passerines, and disagree with all other birds. Correlated with 
the Aigithognathous palate I have always found a peculiar 
structure of the palatine bones. As a rule, in all the Sauropsida 
and Mammalia the old Ichthyopsidan cartilaginous palatine bar 
is aborted, and the palatine bone is formed directly from mere 
membrane. In Ganoids, Osseous fishes and Amphibia, the 
primary rod of cartilage becomes ossified during growth. In 
Passerine birds and in Swifts, and in no other kinds, a large 
“remnant” of the old Ichthyopsidan cartilaginous palatine is 
developed postero-laterally to the main bony bar, becomes 
ossified independently, and then becomes fused with that bar, and 
forms its projecting part, or apophysis. 
A second point is that the Cypselide are very variable. 
Amongst a few dozen specimens, there is far more variation 
