1871.] HULKE — BEPTILTAN SKULL. 205 



Pelecanus having a similar upward slant ; but a closer inspection 

 shows that the likeness is not a real one ; for in Pelecanus the free 

 lower border of the septum, and the floor of the overlying cranial fossa 

 are nearly parallel, the basicranial axis is bent, the front half of it 

 making a large angle with the hinder half of it, while in this 

 Wealden skuU the floor of the cranial cavity is nearly straight in its 

 entire extent, and the apparent inclination of the front half of the 

 basicranial axis is caused by the great downward production of the 

 basisphenoidal swellings behind and the bevelling off of the under 

 surface of the basi-presphenoid in front, with a corresponding 

 decrease of its vertical depth forward, 



I have already stated my reasons for referring Mr, Fox's skull, 

 and therefore mine, to a Dinosaur ; assuming that this opinion is 

 accepted, it remains for me to submit the considerations which 

 lead me to refer it to an Iguanodon. I purposely use the indefinite 

 article, because Iguanodon is commonly spoken of as if the genus 

 had oaly one representative, /. Mantelli, although the mandibles 

 and also the vertebrae referred to this present variations which make 

 the existence of several species very probable, I wish, however, 

 my reference of the skull to the genus Iguanodon to be regarded 

 rather as an attempt awaiting confirmation or correction whenever 

 new and better material for the purpose is discovered. The jaws 

 and teeth, either of which would have determined the reference at 

 once, are lost ; and the circumstances of the discovery of the skull 

 deprive us of the presumptive evidence of its nature which its 

 association with other bones might have afforded ; so that in seeking 

 for a clue by which to connect it with a particular Dinosaur we are 

 limited to what inferences may be drawn from its gisement, and to 

 what we can learn from the intrinsic features of the skull itself. 



As regards the former, the bed from which it came cannot be as- 

 certained ; but we know that the locality is rich in remains of 

 Iguanodon : and with respect to the latter we find the clue, I think, in 

 the obliteration of the sutures ; for these have also appeared to me to 

 be effaced in several mandibles oi Iguanodon which I have examined. 



The loss of the articular end observable in aU these has been 

 occasioned by a fracture across the mandible, and not by the disso- 

 lution of a sutural union. This is plainly the case in the largest man- 

 dible figured by Prof, Owen in his ' British Fossil Reptiha ;' and three 

 reptilian mandibular articular bones in the Rev. Mr, Fox's collec- 

 tion, probably of Iguanodon, also clearly illustrate this. In other 

 Dinosaurian skulls, or portions of skulls, examined with especial 

 reference to this point, I have found the sutures persistent. They 

 are so in Hypsilophodon Foccii, from which this skull is also distin- 

 guished by its large size ; they persist too in Scelidosaurus Harrisonii, 

 of the Lias, and in the Triassic Belodon's skuU, Whether they 

 persisted or not in Megalosaurus is doubtful ; the maxilla, described 

 last session by Prof, Huxley, is not conclusive on this point ; but a 

 maxilla of the aUied Teratosaurus, preserved in the British Museum, 

 proves their persistence in this Saurian. The relative infrequency 

 of Megalosaurian remains in the Isle of Wight (I state this on the 



VOL. XXVII. PART I. Q 



