290 PETRIFACTIONS AND THEIR TEACHINGS. CHAP. III. 



were the bones of the fore-arm (as Professor Owen presumes 

 them to be *), the ulna would be characterised by its ole- 

 cranon or large proximal end, and the radius by its carpal 

 extremity; but the proximal as well as the distal ends of the 

 two bones are in every respect similar to each other, and 

 present the usual characters of metacarpals. 



A slender phalangeal bone, imbedded in another part of 

 the Maidstone specimen (Lign. 63, fig. 5), is probably one of 

 the second series of the fore-foot. 



In Wall-case C, there is a group of four metacarpals, or 

 metatarsals, of a saurian, which differ from the known cor- 

 responding bones of the Iguanodon, and may probably belong- 

 to another species or perhaps genus. These bones are re- 

 spectively 8 inches, 7J inches, 6J inches, and 3| inches in 

 length. 



Ungual Bones of the Fore-foot ? Wall-case C, loivest com- 

 partment. In Lign. 63, Jig. 7, is a reduced outline of a 

 compressed, hook-shaped, ungual bone, with curved lateral 

 grooves, which closely resembles the claw-bone of the 

 Iguana ; it is figured and described in my " Geology of 

 the S. E. of England " (PL III. fig. 1), as probably the nail- 

 bone of the fore-foot of the Iguanodon, but of course upon 

 no other grounds than its presumed analogy; this specimen 

 was seen by Baron Cuvier, who concurred in the probability 

 of the conjecture. 



There are two specimens of this kind in the Case before 

 us. The largest has the distal extremity destroyed : if 

 perfect, it would be four inches in length; the vertical dia- 

 meter of the articular end is 2| inches, and the transverse 

 but little exceeds an inch ; proportions altogether different 

 from those of the unguals of the hind foot. Whether, as the 

 relatively slight humerus, and the elongated metacarpal 

 bones and phalarigeals seem to indicate, the fore limbs of the 

 Iguanodon were long and slender, and the toes armed with 

 curved claws as in the Iguana an inference which appears to 



i Pcdceontograpkical Monograph, 1851. " The radius and ulna lie 

 with their proximal ends next the right hand upper corner of the slab 

 of the Maidstone specimen, the latter being distinguished by its pro- 

 minent olecranon, which is rounded as in the great Monitor ( Varanus 

 . 112. 



