SHUFELDT. | OSTEOLOGY OF THE SPEOTYTO. 595 
umn, being firmly anchylosed together, with their sutures completely 
obliterated when the bird has attained maturity. This is eminently 
the case in the adult skull of the species we have before us, so much so, 
-1n fact, that, with the exception of certain bones that remain perma- 
nently free during life, we will undertake to describe the skull only as 
it presents itself to us in the adult as a whole. In referring to certain 
points for examination, then, in this part of the skeleton, we will have 
to rely largely upon the reader’s familiarity with general anatomy, 
and the extent and position of the bones as they occur in the variously 
shaped heads of immature birds. The major part of the occipital 
lies in the horizontal plane, only that portion which originally con- 
stituted the superoccipital segment and the posterior third of the ex- 
occipital segments curving rather abruptly upwards to meet the mas- 
toids and parietals. All its primary parts are thoroughly coalesced, 
and its articulations with the surrounding bones obliterated, save a fine 
ridge, running transversely, just anterior to the condyle, separated from 
it by a depression which seems to indicate the remains of the occipito- 
basi-sphenoidal suture. Posterior to the foramen magnum the bone rises 
and displays a well-marked “ cerebellar prominence,” with a depression 
on either side of it. On the summit ot this prominence, in the median 
line, just before we arrive at the foramen magnum, we find the super- 
occipital foramen. This foramen varies in size and shape in different 
individuals—in size, from one to two millimetres; in shape, from a circle 
to a transverse ellipse, though it is usually small and circular. It is 
said to be formed by a thinning of the bone due to muscular pressure 
from without and the pressure of the cerebellum from within; in the 
fresh specimen it is covered by athin membrane. Lying in the horizon- 
tal plane, anterior to the cerebellar prominence, is the foramen magnum. 
In shape it resembles a square with the four angles rounded off. Its 
average measurement is five millimetres transversely and four millime- 
tres antero-posteriorly, the latter diameter being encroached upon by 
the occipital condyle in the median line. The occipital condyle is sessile, 
though raised above the level of the basis cranii, hemispheroidal in form, 
with a minute notch marking it posteriorly in the middle. Immediately 
beyond the condyle appears a depression, on either side of which are 
seen the precondyloid foramina for the transmission of the hypoglossal 
nerves; they are extremely small, and open anteriorly. External to 
these, lying in the same line transversely, is seeu a group of usually 
three foramina for the passage of the glossopharyngeal and vagus 
rent universal adaptability; in fact, its truth became one of the treasured results of 
my university education. Several years elapsed before I was again allowed to renew 
my favorite study, during which time the vicissitudes of my life allowed but little op- 
portunity to follow the many advances in this important science, and when the day 
finally came, and the above monographs were written, and I drew the plates illustrating 
them, I was many hundreds of miles, and for several years, removed from all that one 
has access to in large cities and scientific circles. From this standpoint they must be 
judged, then, and for this reason did errors and theories creep into them that are ‘‘ so 
dangerous to the credit of comparative anatomy.” It is believed that the Osteology of the 
Cathartide will be largely exempt from such errors. The author deems it entirely un- 
necessary to enter upon the merits or demerits of any theory here, simply announcing 
in connection with what has already been said above, that he believes the vertebral 
theory of the cranium to be untenable in the light of modern science, and incompat- 
ible with modern thought. Aside from the theory involved, it is hoped that the purely 
anatomical facts will be found to be correct as given, aud as any attempt to eradicate 
the theory from these memoirs would simply result in a rewriting of the whole, the 
author has allowed them to stand substantially as they first appeared, simply offering 
his reader the above explanation and making such changes as he deems hest through 
the medium of foot-notes; introducing into the body of the paper only such material 
and facts as he has been able to gather since, bringing the whole up to the standard of 
a revised edition. 
