750 GEOLOGICAL SURVEY OF THE TERRITORIES. 
more prominent in Gypogeranus than they are in the largest of our Con- 
dors, whilein Neophron percnopterus the pterygoids stand well away from 
the basi-sphenoid and no such processes are present. In Polyborus not 
the slightest evidence of them exist, but in Aquila and Circus we find 
diminutive sharp spines jutting from the usual points, but they do not 
possess articular extremities, nor do they ever meet the pterygoids in 
these birds. It will be remembered that we found them in quite a num- 
ber of the American Owls, and we believe they are present.in.all of them. 
Gently inclined upwards, very long and robust, we find the basi-pre- 
sphenoid in all of the Cathartide, carrying out its functions in the me- 
dian cranial plane. Above it has become thoroughly blended with the 
interorbital septum and the mesethmoid, below it is rounded and smooth, 
and aifords the common articular surface for the pterygoids and pala- 
tines. In Pseudogryphus it has a length of four centimeters, and in C. 
aura develops a little spine anteriorly that projects beyond the meseth- 
moid. 
We show in our cut of the rear view of the cranium in Pseudogryphus 
how the region of the occiput is bounded by the superior muscular line, 
both laterally and above; this line is well marked in all of these Vul- 
tures. The lines at the sides are quite ridge-like in the California Con- 
dor, parallel and in the vertical plane, while the line forming them above 
is a long, shallow arc, with its concavity towards the cerebellar promi- 
nence; this is also the case in C. atrata. In Cathartes aura the side 
lines are curved outwards, while the superior line is broken at its middle 
point, which point is carried down on the cerebellar prominence for about 
one-third of its distance from above, in the median plane, where the ex- 
tremities of the broken line join it at a gentle curve on either side. 
This is nearly the pattern as seen in G. papa, but in S. gryphus we again 
find it as we described it in the Northern Condor, only we have in the 
former a slight inclination for the point to come down on the promi- 
nence. 
If we remove a section of the vault of the cranium, and this has becn 
done here in C. aura and Catharista, in specimens of skulls of these birds 
that have been in collections for several years ,* we find that the internal 
and external layers or the cranial tables are very thin, and that a fair 
amount of dipldic tissue is placed between them, especially towards 
the occipital region, where, as we approach the locality of the internal 
ear on either side, it becomes several millimeters thick; the cellular 
network being more or less coarse in texture. The internal walls of the 
brain-case as thus exposed are smooth, being traversed only here and 
there by vascular tracts and grooves for the exit of certain nerve 
branches. The fossz designed for the reception of the different ceph- 
alic lobes are moderately well separated, the one that contains the 
epencephalon being the most distinct, aided asit is by the internal con- 
cavity of that external feature of the occiput that we described above 
as the cerebellar prominence; the usual transverse groovelets do not 
mark this section here on the internal table. This distinctness is further 
assisted by thin horizontal off-shoots from the united bones of the ear- 
cell. The internal auditory foramen is unusually large and predicts a 
correspondingly good size for this important nervous branch; the same 
remark applies to the trigeminal and its orifice of exit. Remarkable 
depth and space is allotted to the fossa for the lodgment of the hypophy- 
sis, the “sella turcica,” as this receptacle is known by in anthropomy, 
“For changes that may possibly take place, see author’s remarks in Osteology of 
Nat ludovicianus excubitorides (Bull. Geol. and Geogr. Surv. of the Terr., Vol. VI, 
0.2). 
