92 REPORT — 1841. 



It is the fortunate preservation of the two articular, or oblique processes, 

 at one of the extremities of the annular part of this fine cervical vertebra, 

 now in the Mantellian Collection, British Museum (No. ^j|), that has enabled 

 me to correct the error into which the Founder of that noble collection has, 

 in this instance, fallen : the flat oblong articular surface of each of these 

 strong and -well-marked oblique processes looks downwards and outwards, 

 determining them to be the posterior pair ; and they overhang the concave 

 extremity of the body of the vertebra, determining that to be the posterior 

 extremity. The opposite, or anterior end of the body of the same fossil, is 

 convex. The few other large convexo-concave vertebrae from the Wealden 

 of Tilgate correspond with the one here described in these important charac- 

 ters of the genus Streptospondylus, and equally differ from the vertebrae of 

 the Iguana, Monitors, and all other existing Sauria. Of the fossil cervical 

 vertebra, 6 inches long, the anterior extrenuty of the body is further indicated 

 by the position of the costal tubercle, or transverse process, which is deve- 

 loped as a strong obtuse ridge from the middle part of that half of the cen- 

 trum which is nearest the convex articulation. Beneath this ridge the sides 

 of the body are concave, and converge to a broad ridge, which terminates 

 the anterior part of the lower surface of the vertebra, and corresponds with 

 the process given off from that part in the cervical vertebrae of the Crocodile. 

 A second concavity, at the upper part of the side of the body, separates the 

 transverse process, or ridge, from the base of the neural arch ; from which a 

 second, or upper transverse process is developed for the attachment of the 

 tubercle of the rib. 



The neural arch has been crushed down upon the centrum, and its anterior 

 oblique processes and spine are broken away ; the upper, non- articular part 

 of the strong diverging posterior oblique processes is convex. 



In the museum of Mr. SauU, F.G.S., Aldersgate Street, there is a cervical 

 vertebra of the great Streptospondylus associated, as in the Mantellian Col- 

 lection, with vertebrae of the Iguanodon and Cetiosaurus, all of Avhich have 

 been washed out of the submarine Wealdan beds at the south side of the 

 Isle of Wight, and thrown on shore near Culver Cliffs and Brook Point. 



The lower half of the sides of the centrum of the vertebra of the Strep- 

 tospondylus are, like the preceding vertebra from Tilgate, concave and ob- 

 liquely compressed, so as to converge to the anterior part of the under sur- 

 face, which thus presents a triangular form, with the apex forming the obtuse 

 anterior ridge, and the base turned backward and somewhat flattened. Each 

 lateral concavity is bounded above by a short but broad transverse process, 

 developed from the anterior half of that part of the centrum, and terminated 

 by an oblong flattened surface for the articulation of the head of the cervi- 

 cal rib ; which surface is about twice as long in the antero-posterior as the 

 vertical direction. Above this process the centrum is again concave. The 

 base of the neurapophysis is anchylosed to nearly the whole antero-posterior 

 extent of the centrum, the course of the original straight suture being readily 

 discernible. An upper transverse process is developed from the side of the 

 base of the neurapophysis, affording a broader surface for the tubercle of the 

 cervical rib than does the lower transverse process. Above the upper trans- 

 verse process the neurapophyses converge obliquely to the base of the spinous 

 process. The line of tlae base of the spine inclines forwards, and the thick- 

 ness of the spine diminishes in the same direction. The difference in the 

 height of the neural arch, and in the configuration of its external surface, 

 which both the cervical vertebrae of the great Wealden Streptospondylus pre- 

 sent, when compared with the dorsal vertebrae of the smaller specimens from 

 the older oolite formations, is very great ; and the more remarkable, as in the 



