246 MEMOIRS OF THE CARNEGIE MUSEUM 
men which passes through the lower margin of the exoccipital just at its point of 
union with the basioccipital and enters the posterior margin of the foramen mag- 
num a little in advance of the occipital condyle. This foramen is most undoubt- 
edly the foramen which gave exit to the hyoglossal nerve. 
At the point where the basioccipital processes diverge anteriorly on the median 
line, just where union is effected between the basioccipital and basisphenoid bone, 
there is a deep foramen penetrating upward which the writer interprets to be, after 
the analogy of the crocodilan skull, the median eustachian foramen. 
In addition to these foramina there are in the superior borders of the orbito- 
sphenoid bones, where they unite with the frontals, small notches which may have 
given exit or entrance to blood vessels. 
The attentive study of the foregoing account of the foramina of the cranium 
of Diplodocus reveals the fact that there is a close correspondence in the location 
of the various exits for the nerves of the brain between the skull under considera- 
tion and the skull of Iguanodon, a cast of the brain cavity of which was made by 
Professor Andrews and is beautifully delineated in the paper to which reference 
has been given. The brain of Diplodocus was however much more compressed 
antero-posteriorly. The cerebellum was less strongly developed, judging from a 
east of the interior of the brain cavity of specimen No. 2673 (U. 8. N. M.), which 
lies before the writer. The pituitary body in the brain of Diplodocus was not as 
strongly developed as in the brain of Iguanodon, though the impression of the in- 
terior cavity of the skull of Diplodocus before the writer is in many respects not as 
perfect as the impression secured by Professor Andrews, and it is therefore possible 
that the latter statement may hereafter require to be somewhat modified. 
CERVICAL VERTEBR. 
Tur ATLAS. 
Unfortunately, in all the material, which has been collected by the different ex- 
peditions sent out by the Carnegie Museum, no specimen of an atlas, which could 
unmistakably and positively be referred to Diplodocus, was found. The American 
Museum of Natural History was so fortunate as to secure an atlas with the skull 
(No. 969). The elements are disarticulated and somewhat crushed, nevertheless not 
so much so as to render it impossible to easily and correctly adjust the parts. The 
atlas figured by Professor Marsh (‘‘ Dinosaurs of North America,” Plate XX VII. 
Figs. 1 and 2), and reproduced by Mr. Hatcher in his account (Memoirs of the Car- 
negie Museum, Vol. I., p. 19, Figs. 4 and 5), if the atlas of Diplodocus, is undoubt- 
