206 PKOCEEDIKGS OF THE GEOLOGICAL SOCIETY. [Jan. 25, 



authority of a verbal communication from Mr. Fox) renders it less 

 probable that the skull belonged to this Dinosaur than to an Iguano- 

 don. In the ornithocephalic skull of Struihiosaurus, Bunzel, the 

 sutures also disappear ; but its broad rounded occiput, its large 

 downward slanting paroccipital processes (shown in the figures ac- 

 companying Dr. Bunzel's description), and the absence of the basi- 

 sphenoidal swellings so conspicuous in my Wealden skull completely 

 distinguish it from this. 



EXPLANATION OF PLATE XL 



Supposed skull of Iguanodon, froon Brooke, Isle of Wight. 



Fig. 1. View of right side of the skviU. 



Fig. 2. View of interior of the same. 



Fig. 3. View of upper surface of the skulL 



Fig. 4. View of posterior surface. 



Fig. 6. View of under surface : pa, parietal crest ; t, temporal fossa ; sp, suspen- 

 sorial process ; ot, occipital tuberosity- ; bs, basisphenoid ; bps, basi- 

 presphenoid ; os, orbitosphenoid ; hpf, hypophysial fossa ; /, foramen 

 magnum ; c, posterior opening of carotid canal ; c', anterior opening 

 of same ; ii, v, vii, viir, ix, foramina of the respectire pairs of nerves. 



DlSCTTSSION. 



Prof. HtrxLET congratulated the Society on the progress being 

 made in our knowledge of this interesting group of Reptiles and of 

 their ornithic affinities. 



Mr. Seeley remarked on the similarity of the internal cavity of 

 the skull to that of IchthyosoMrus. Some of the external charac- 

 teristics differed much from what he was acquainted with in other 

 Dinosaurian skulls, which, in the base of the skull, more closely re- 

 sembled those of ordinary lizards. He considered that the affinities 

 of Dinosaurs hitherto demonstrated were in the direction of Tdeo- 

 saurus, from which the position of what were supposed to be the 

 optic lobes in this skull materially differed in being more reptilian. 

 On the whole, from its want of similarity to Hypsilophodon, he was 

 not prepared to accept this skull as that of an Iguanodon, and 

 thought that seme doubt attached to its affiliation with the 

 Dinosaurs. 



Mr. HxjLKE briefly replied, and observed that he had limited his 

 speculations to those which legitimately arose from the facts before 

 him. 



