ROOM III. SPINAL COLUMN OF THE IGUAXODON. 259 



In the " Geology of the South-East of England" (p. 307), 

 several large convexo-concave vertebrae from Tilgate Forest 

 are described as presenting the true lacertian form, being 

 concave anteriorly, and convex posteriorly, as in the Iguana, 

 Monitor, Crocodile, &c. ; but in 1841, Professor Owen ascer- 

 tained that the relative position of these vertebrae in the 

 skeleton was the reverse of the ordinary type, the convexity 

 being anterior ', and the concavity posterior. A similar devia- 

 tion from the usual rule had long previously been detected 

 by Baron Cuvier, in a fossil crocodilian found at Honfleur, 

 (figured and described in " Ossemens Fossiles" tome v. p. 155) ; 

 and which was referred by Geoffrey St. Hilaire to the genus 

 Steneosaurus, but has since been named by Herm. von 

 Meyer, Streptospondylus (reversed spine) ; an objectionable 

 term, since the same character is present in several fossil 

 genera, as well as in existing mammalia ; and the vertebrae 

 from Tilgate Forest were assigned by Professor Owen to the 

 same genus as Streptospondylus major. 1 



But notwithstanding the high respect I entertained for the 



n found anatomical knowledge of the Hunterian Professor, 

 3uld not divest myself of the idea that this opinion was 

 untenable, from the fact that all the convexo-concave ver- 

 tebrae hitherto found in the Wealden were cervical j it was, 

 indeed, this circumstance, together with the extreme rarity of 

 this type, which deterred the Rev. W. D. Conybeare and 

 myself, at the commencement of my researches, from as-, 

 signing them to the Iguanodon. 2 



The inspection of a large anterior dorsal vertebra of the 

 convexo-concave system in my collection, first suggested to 

 Dr. Melville the idea that this bone, as well as the cervicals 

 above mentioned, belonged to the Iguanodon, and he spared 

 neither time nor trouble in endeavouring to ascertain the 

 correctness of this opinion : to him, therefore, alone is due the 



1 " British Association Reports," 1841, p. 91. The eminent author 

 appears, however, to have entertained some doubts whether the vertebrae 

 in question might not belong to his genus " Cetiosaurus ; " but he dis- 

 misses the suspicion with the remark, " that the general constancy of 

 the vertebrae of the same Saurian in their antero-posterior diameter 

 forbids the supposition of a vertebra six inches in length in the neck, 

 being associated with one three inches in length in the back," p. 96. 



2 See " Geology of the South-East of England," p. 307. 



