254 O. C. Marsh—American Jurassic Dinosaurs. 
Little has been known hitherto of the brain of Dinosaurs, 
of the entire bodies, estimated from corresponding pe ot 
each skeleton, was as 1 to 1000. It follows that t 
Stegosaurus was only +4, that of the Alligator, if the weight 
of the entire animal is brought into the comparison. If the 
contrast would be still more striking. This comparison, gives, 
of course, only approximate results, and some allowance should 
be made for the proportionally larger brain in small animals. 
Outline of posterior part of skull and brain-cast of Morosaurus grandis, Marsh ; 
uperior view, one-fourth natural size; ol. olfactory lobes; ¢. cereb: ge 
pheres; op. optic lobes; on. optic nerve; cb. cerebellum; m. medulla ; 
occipital condyle. 
The brain of Stegosaurus ungulatus is clearly of a lower type 
than that of Morosawrus, which, as the writer has shown, me 
several times smaller in diameter than the neural canal in 18 
