416 BRITISH FOSSIL REPTILES. 



aspect, in Plates 36 and 37 of the present History, will suffice to satisfy even 

 a superficial comparative osteologist that they must belong to different species, if 

 not genera, of Saurians. They are both from that anterior part of the tail where 

 the vertebrae still retain the zygapophyses and send off the transverse processes 

 (dia-pleur-apophyses, d-pl) from the base of the neural arch at its junction with the 

 centrum : they are nearly, if not quite, homologous vertebrae. If No. 28.633 

 (PL 37) belonged, as its original possessor had marked it, to his genus Peloro- 

 saurus, — No. 10.390 (PI. 36) of the earlier collection of fossils, originally marked 

 Iguanodon, could not belong to the same genus. 



It will be presentlv show^n that the caudal vertebra (PI. 37) marked Pclorosaurus 

 by Mantell in his latest collection of fossils, although much more like the corre- 

 sponding vertebra of Iguanodon than is the vertebra (PI. 36) so called in the 

 first Mantellian collection, yet presents such differences as might have justified 

 a generic separation from Iguanodon, if even the indication of the distinct genus 

 of huge Wealden Saurian had not been afforded by the hollow limb-bone of 4^ feet 

 in length. 



The generic distinction of the above-cited vertebra from the first collection 

 (PI. 36), selected by Mantell, in his memoir of 1850, to illustrate the vertebral 

 characters of the new genus Pelorosaurtis, founded on the later acquired fossil 

 limb-bone, is much more strongly marked as compared with Iguanodon, or with 

 the anterior caudals marked Pelorosaurus in the last collection. 



In 1850, therefore, the persevering investigator of the geology of the South-East 

 of England had evidence of two gigantic genera of Wealden Repiilia distinct from 

 his Iguanodon, afforded by vertebrae, and he possessed also similar evidence 

 afforded by bones of the limbs. 



Those of the latter which were destitute of a medullary cavity he unhesitatingly 

 referi'ed to my genus Cefiosaurus, and he founded upon the long-bone with the 

 medullary cavity the genus Pelorosaurus ; but, with respect to the vertebrae, he chose 

 to select for the Pclorosaurus those that had been previously demonstrated by me 

 to present the Cetiosaurian character. 



Pelorosaurus Conybearii. 



The anterior caudal vertebra (PI. 37) differs from the corresponding vertebrae of 

 Iguanodon, and is here referred to Pelorosaurus, on ihe authority of the Mantellian 

 label, according to which it was purchased as belonging to that genus, and is so 

 entered in the Register of the British Museum, under the number 28.633. 



