I 43. THE HYLiBOSAURUS. 437 



of stone ; numerous vegetable remains, and carpolithes, or 

 seed-vessels of the Clathraria (ante, p. 399), were detected 

 in reducing the size of the mass.* 



I subsequently obtained many bones of this reptile from 

 a bed of clay near Crawley ; and a most interesting specimen 

 of part of the vertebral column, comprising nearly thirty 

 dorsal and caudal vertebrae, with many dermal bones and 

 spines, ribs, &c. 



Dermal bones and spines. \ The structure of the dermal 

 bones is very peculiar, and closely resembles that of the 

 ligamentous fibres of the corium, or skin, and seems to have 

 resulted from an ossified condition of the dermal integu- 

 ment. J Upon inspecting the surface exposed by a trans- 

 verse fracture of the oval scutes, minute osseous spicule, 

 decussating each other at right angles, are visible to the 

 naked eye ; and under the microscope, the same arrange- 

 ment is found to prevail in the minutest bony fibres ; the 

 medullary canals have fine lines radiating from them. 



I have very lately been able to ascertain that the same 

 internal structure characterizes the spinous bones (Plate 

 IV. 5, 6) ; and this fact tends to confirm my opinion, that 

 they are also ossified dermal processes, which formed a 

 longitudinal crest along the back of the animal. § 



* For further particulars see ray Geology of the South-East of Eng- 

 land, p. 316. PI. V. of that work is an excellent lithograph of this 

 specimen, by Mr. Pollard, of Brighton. 



f Medals of Creation, vol. ii. p. 704:. 



X See my Memoir on the Fossil Eeptiles discovered in Tilgate 

 Forest, Philos. Trans, for 1841. 



§ The following are Professor wen's remarks on the dermal scutes : — 



" By the kindness of Dr. Mantell I have been favoured with the 

 means of submitting the structure of a dermal scute to microscopical 

 examination. The medullary canals, which are stained brown, as if 

 with the hematosine of the old reptile, differ from those of ordinary 

 bone, in the paucity or absence of- concentric layers. They are situ- 

 ated in the interspaces of straight, opaque, decussated filaments, which 

 frequently seem to be cut short off, close to the medullary canals. 



