140 Mr. H. G. Seeley on Prof. Owen's 
of structure. Immediately afterwards, however, it is justly 
remarked that the skull is enormously large in Dimorphodon 
even for an Ornithosaurian. It is also remarked that “ the 
parietals swell out slightly at the temporal foss, indicative of 
the size and saurian position of the mesencephalon "—that is, of 
the optic lobes. It is due to a correct appreciation of this fact 
to mention that in the Report of the Syndics of the Cambridge 
specimen existe was about to be figured, which would 
show that the size and position of the mesencephalon was not 
saurian, but avian. or was Prof. Owen unaware of the 
value of this character; for in the ‘Comparative Anatomy of 
the Vertebrates’ it is said of the bird’s brain, “ It differs from 
the brain of every other class in the lateral and inferior posi- 
tion of the optic lobes." 
I know nothing of the brain of Dimorphodon; but the 
second figure represents the outline of the cerebrum and cere- 
bellum in an Ornithosaurian from the Cambridge Greensand. 
Another specimen* shows the lateral and inferior position of 
the optic lobes. 
Strix otus. Pterodactyle. Ornithorhynchus, 
0, optic lobes; c, cerebellum. 
* Figured in my work on the Ornithosauria. 
