SHUFELDT. ] OSTEOLOGY OF THE CATHARTIDZ. 739 
The palmar aspect of all the long digits show one or more such aerial 
penetrations, while the blade-like expansion of the first phalanx of 
second metacarpal seems to be absolutely riddled by these foramina, 
lending to it a decidedly honeycomb appearance. 
The femur is the only bone of the pelvic limb that enjoys the condi- 
tion we are discussing. In it air gains access to its interior through a 
single opening (C. aura), or, aS in most cases, Several of them, on the 
anterior aspect of the bone, below the great trochanter, close to the 
prolongation of its curling crest. In Pseudogryphus we discover a few 
additional ones on the upper face of the trochanter major, beyond the 
usual group. 
We may say, then, that as arule for the Cathartide, the only bones 
in their skeletons that do not receive air into their interiors through 
pneumatic foramina are certain portions of the cranium, lower maxilla 
and pelvis, the hyoid arch, the atlas, the coccygeal vertebre, including 
the pygostyle, the bones of the pelvic limb below the femur, and all sesa- 
moids and ossifications pertaining to the sense organs. 
Passing to the Falconide and the Old World Vultures, we observe in 
the latter that although they have the greater share of their skeletons 
pneumatic, it is not nearly so perfect a condition as it has just been 
shown to be in our Cathartide. In Neophron percnopterus the axis is 
non-pneumatic, as are all the segments of the pectoral limb save the 
humerus. To these musti be added the bones that we have just passed 
over and enumerated in the family in hand, as being so. 
We find the furculum in the Vulturine a bone not nearly so well 
erated as we have described it for the New World Vultures, it is still 
less so in Gypogeranus, and the same remarks will apply here in gen- 
eral for the remainder of the skeleton of this bird that we have this 
moment made in regard to the Vulturine. In general they are equally 
applicable to the remainder of the family Falconide. We believe that 
we will not go far astray in laying it down as a rule for the entire order 
Raptores, that this attribute of the skeleton seems to have arrived at 
its acme in Catharista atrata, exists to a greater or less degree in all of 
the American Vultures, then becomes less marked as we pass to the 
vulturine Raptores of the Old World, among which we believe that the 
clavicles will be found to be far less pneumatic throughout, though the 
femora still remain so, down among the diurnal and nocturnal Raptores 
of both continents, until we arrive at such forms as Speotyto, where we 
know the entire pelvic limb to be exempt from this condition, and that 
air is excluded from more than half the bones of the skeleton of this 
ground-abiding Owl. 
Having dwelt now, and we trust with sufficient thoroughness, upon 
the present classification of the Cathartide, their leading and more 
important external similarities and differences, and then touched upon 
some of the more general characteristics of their skeletons, we will pro- 
ceed to investigate these latter more in detail, beginning, as we have 
done in former memoirs, with the skulls of the species to be treated. It 
is the object of the author during this investigation to keep these two 
things prominently before his reader, the first being the prime object of 
the work we have to do, viz, an accurate description of the skeleton of 
each species of the family as far as our material will allow us to give it; 
and, secondly, from time to time, to compare the principal bones of 
these birds with those of members of their own family, and then with 
those of other families of near kin; our second aim being, so far as oste- 
ology will justify it, to test the all-important question as to whether 
the Cathartide have been wisely arranged and distributed in the genera 
