SHUFELDT. ] OSTEOLOGY OF THE CATHARTIDA TAT 
versely. Quite a decided constriction exists between the mastoid and 
orbital processes and the mandibular end. The portion bearing the 
outer condyle is produced, outwards, forwards, and upwards, as a sub- 
cylindrical, stout apophysis, having in its extremity the deep, conical 
pitlet for the reception of the process upon the squamosal end of the 
infraorbital style. 
The pterygoids are horizontally compressed and exhibit upon their 
mesial edges the elongate facettes for the pterapophysial processes of 
the basi-sphenoid ; these facettes are towards the anterior and broader 
ends of the bones. The posterior extremities of the pterygoids are con- 
stricted and twisted upon themselves, so as to bring their articular fac- 
ettes to meet those that were described for their reception upon the 
quadrates, while the anterior ends are dilated to afford the necessary 
articular surface for the palatines. These bones do not meet anteriorly 
in any of the Cathartide, but form the usual palato-pterygoidal articular 
apparatus for the rostrum of the sphenoid. 
We cannot state at present with any degree of confidence whether 
the orbito-sphenoids develop in these birds from separate centers of 
ossification or not; at any rate, as a general thing, the orbital septum 
is quite complete in the smaller varieties of the family, but in the Con- 
dors and G. papa large and more or less circular deficiences, most usually 
only one, exist in this partition, about its middle. This sometimes fuses 
with the perforation that is found just anterior to the optic foramen. 
In all of our skulls of C. atrata this inter-orbital wall is entire and quite 
thick, but in all, with the exception of this Vulture, it is in either orbit, 
produced out, by division above, in connection with the ethmoidal wings, 
to the vault, and in so doing leaves a covered duct (double in Pseudo- 
gryphus) for the passage of the first pair of nerves from the rhinence- 
phalon to the rhinal chamber beyond. So deficient are the walls of this 
osseous duct in C. atrata that it is really reduced to a canal. Even in 
Cathartes aura we occasionally find foramina, due to the too great thin- 
ning of the walls, present, and opening into the passage. In the back 
part of the roof of the orbit we find the usual circular foramen for the 
orbital vein, with a shallow groovelet leading from it in all of the Cath- 
artide. 
In Neophron this arrangement is like it is in the Falconida, 7. e., an 
open channel is provided for the nasal nerves. 
The orbital septum sustains one other perforation, already referred 
to, and can be best described by saying it is a piercing of the partition 
immediately in front of the orbital foramen proper, thus allowing very 
nicely the passage of the branches of the crossed optic chiasma. Other 
nervous foramina are found to be distinct. The only example of the 
sclerotal plates that we have are a set from the eyes of a specimen of 
C. aura. In this Vulture they number fifteen in each eye, are very broad, 
overlapping each other by about one-fifth of the extent; their corneal 
margins are turned outwards, while their sclerotal ones are reflected in 
the opposite direction. We have but little doubt that when opportu- 
nity for examination offers, this description will apply very closely for 
these platelets among others of the Cathartida. 
All of the cranial segments, or rather such of them as usually go to 
form the brain-case, have become thoroughly anchylosed in this family. 
Original sutures, boundaries, and land-marks have disappeared in the 
adult birds, leaving not a trace behind them to acquaint us as to the 
position of the primoidalelements. A study of the superior aspect of the 
skull has already been submitted to the reader and its leading features 
sufficiently well dwelt upon; now, viewing the cranium from a lateral 
