WEALDEN FORMATIONS. 51 



Integument (?) of the Iguanodon. Tab. XV, fig. 8. 



In that part of the specimen of the skeleton of the young Iguanodon, figured in 

 Tab. I, which is in the Museum of Mr. Bowerbank, some portions of a layer of dark, 

 finely granulated carbonaceous matter, were found imbedded between the ribs, near the 

 middle of the side of the trunk, and slightly adhering to the discoloured matrix : this 

 layer is very probably, as Mr. Bowerbank believes, a part of the integument of the 

 Iguanodon. Of the best preserved portions of this substance, the largest is an oblono- one, 

 8 lines in long diameter ; another is 6 lines in diameter ; and both are about 1 line in 

 thickness. Supposing the Iguanodon to have been covered by epidermal scales like 

 those of the Iguana, and of proportional size, a single scale would cover from four to 

 six times the extent of corium which is shown by the largest of the above specimens, 

 on the supposition that they are parts of the true skin of the Iguanodon. 



The firmer and more enduring parts of the substance here displayed seem to 

 have consisted of coarse fibres, irregularly interlacing each other; these form the 

 darker parts which rise above the surface and give it, when viewed by the naked eye, 

 a subgrannlar character; the depressions indicate the interspaces of the fibres, and 

 contain fine particles of a substance of a lighter colour. I have not been able to detect 

 any clear traces of ultimate organic structure in the black carbonized remains of the 

 fibrous tissue. 



So much of structure as is discernible accords well with that of the corium of a 

 tough and thick skin ; but no conclusions can be satisfactorily deduced from the small 

 portions here preserved, as to the nature of the defensive covering, epidermal or osseous, 

 of the corium of the Iguanodon. The experienced microscopist to whom I am indebted 

 for the opportunity of inspecting these rare and interesting specimens, writes to me : 

 " I have examined the skin with the greatest care with my microscope, but I cannot 

 find any indications of scales." My own observations have led to the same result. 

 The visible character, however, of the surface of the supposed fossil skin of the 

 Iguanodon, is not inconsistent with that of the vascular corium of a reptile which 

 nourishes an overlying epidermal scale, or osseous plate or scute, either of which parts, 

 if present in the living animal, would be most probably much larger than the largest 

 of the fragments that have been here preserved. The chief difference between the 

 corium of a squamate and that of a loricate reptile, is its less thickness in the latter 

 where it underlies bone, than where it supports a scale, as in the squamate species. 



Allowing for the extreme shrinking and condensation of skin which has become 

 carbonized in the present rare instance, and has resisted the common result of the 

 dissolving agencies, I should infer from these fragments that they might have originally 

 been of that thickness which is consistent with an external covering of epidermal 

 material. 



