MORPHOLOGY OF THE VERTEBRATE SKULL 17 
(aa ha = > 
Vi f oe = aes 
No. 5753.A.M. 
Fig. 8 Brain case of a theropod dinosaur Allosaurus agilis. (Osborn, Mem. 
Am. Mus. Nat. Hist.,n.s., vol. 1, pt.i., text fig. 10, p.17.) Right side seen obliquely 
from above. Determination of foramina by the present writer with the kind 
assistance of Dr. F. von Huene. 
The alisphenoid (marked O.sp.) is seen to be anterior to the prootic and prootic foramen (V), external 
to the carotid canal (car. in.) and chiefly posterior to the openings for nerves II, III, IV. The lateral wing 
marked ? P.sp. may represent the orbitosphenoid. 
In the Dinosaurs (figs. 8-10) the orbitosphenoids are probably 
represented by the lateral wings of the elements called by Dr. 
von Huene ‘presphenoids.’ These lateral wings are behind the 
ethmoids, below the frontals and lateral to the median presphe- 
noid, they are also in front of the openings for nerves II, III, IV. 
The chief differences then between the true orbitosphenoid wings 
in Dinosaurs and the orbitosphenoids of mammals is that the 
latter ossify separately from the median presphenoid whereas 
