ike Head in Orniihomrtrs. 25 



reptilia and lower animals as of mammals; only in the reptile* 

 they are not closed-in in front by bone, while in mammals 

 they are. But in no sense, except in form, can the olfactory 

 lobes of this specimen be called mammalian ; for they obviously 

 never sent filaments direct to supply the olfactory sense, but 

 apparently forwarded the olfactory nerve in a closed tube. 

 Thus in not passing through the ethmoid, but through the 

 frontals, the olfactory lobes approximate towards birds', but 

 differ from all birds', so far as I am aware, in their great size. 



I conclude, then, that the frontal bone under consideration 

 is only closely comparable with birds', and that it diverges 

 from birds' in ways which are not paralleled in other animals. 



Elsewhere I have described and figured all the cranial 

 structures of Ornithosaurians which theWoodwardian Museum 

 contains t; and I propose now, with the notice of an additional 

 imperfect bone which may be the maxillary, to point out ex- 

 actly how much is known of the Ornithocheiroid brain and 

 skull, and how they resemble and differ from those of other 

 animals — only remarking that the results arrived at can be 

 but of a general nature, since the specimens are few, imper- 

 fectly preserved, of different sizes, and obviously belong to 

 two or more genera, each bone perhaps pertaining to a different 

 species. 



First, then, to reconstruct the brain. The materials are 

 a transverse section of the brain-case in front of the optic lobes, 

 a natural mould of the upper part of the brain showing the 

 form of the cerebrum and part of the cerebellum, and an indi- 

 cation of the optic lobes on the under surface, an ethmo- 

 sphenoid bone apparently closing in the brain in front, and part 

 of a frontal bone closing the brain in above ; so that, with very 

 unimportant and small parts, the structure of the brain-case is 

 now known. 



I suppose the form of the brain-cavity to indicate with ap- 

 proximate accuracy the form of the brain, in which case the 

 Pterodactyle's brain must have been very like what is here 

 drawn (PI. II. figs. 6, 7) ; for in only one or two points is 

 there likelihood of error : the cerebellum may be here made 

 too long, and the depth of the cerebrum may be made too 

 little ; for there is evidence that it is nearly as deep as it is 

 long. 



When the brain is seen from above (fig. 6), there is no diffi- 

 culty in recognizing it as an evident modification of the avian 

 outline, chiefly remarkable for the enormous size of the cerebral 

 and olfactory lobes, and the small size of the cerebellum, by which 



* Serpents not excepted. t ' Tlie Ornithosauria.' 



