128 REPORT— 1841. 



The following are dimensions of this interesting fossil : — 



In. Lin. 



Length of the base of the neurapophysis* 4 6 



From the base of the neurapophysis to the middle of the base \ ? ^ 



of spinous process j 



From the base of the neurapophysis to the posterior part of 1 en 



the base of spinous process j 



From the base of the neurapophysis to the anterior part of I q c 



the base of spinous process J 



Antero-posterior extent of base of spinous process 6 6 



Transverse diameter of spinal platform 8 6 



Transverse diameter of conjoined bases of neurapophysesf ..40 

 Extent of spinal platform beyond hind part of base of neura- 1 4, ^ 



pophysis J 



The spinous process is broken off near its base in this specimen, which is 

 otherwise remarkably entire, considering that it was washed out of the sub- 

 merged beds of the Wealden and cast on the south shore of the Isle of Wight. 

 It was found near Culver Cliff. 



The characters thus obtained from two different parts of the vertebrae of 

 two Iguanodons from distant localities, certified to belong to that genus from 

 the association of one of the parts, viz. the vertebral centrum, with many other 

 characteristic bones of that reptile, have their value increased from the cir- 

 cumstance of the obscure and unsatisfactory manner in which the vertebral 

 characters are exhibited in the celebrated specimen from the Maidstone 

 quarry. The eight vertebrae originally forming a continuous series in this 

 specimen are from about the middle of the back ; the antero-posterior dia- 

 meter of each is 3^ inches. Little more can be determined from these or from 

 the detached and crushed dorsal vertebrae in this specimen, except the flatten- 

 ing of the sides of the vertebrae and their convergence to the lower surface, 

 the slight concavity of both articular extremities, the height of the neural 

 arch, and the strength and length of the transverse and spinous processes. 



With the evidence afforded by the previously described specimens, the cha- 

 racters afforded by the following detached vertebrae from the Tilgate strata may 

 with confidence be applied to the further elucidation of the osteology of the 

 Iguanodon. 



An anterior dorsal vertebra (No. ^, Mantellian Collection), having the 



following dimensions of the centrum, — 



In. Lin. 



Antero-posterior diameter 3 11 



Vertical diameter of articular end 4 1 



Transverse diameter of articular end 3 2 



measures, from its under surface to the posterior part of the base of the 

 spinous process, 8 inches. The broad and high neural arch is anchylosed 

 with the centrum, but the nearly straight line of suture is indicated by nume- 

 rous puckered rugae and striae. The transverse process extends from the side 

 of the neurapophysis ; its base is vertically oval, measuring 21 inches by 2 

 inches. The neurapophysis expands above this surface into a broad plat- 

 form, with a thick i-ough external free border, probably fi'actured. The plat- 

 form is supported by a buttress-like ridge, rising vertically from the posterior 

 angle of the base of the neurapophysis, and expanding as it ascends to blend 

 with the under part of the overhanging platform. Behind this buttress-is a 



* This doubtless gives the length of the centrum to which it was attached, 

 t At their anterior and broader part. 



