504 BRITISH POSSIL REPTILES. 



The half or ramus of the lower jaw preserved is represented by the dentary element, 

 containing many of the characteristic teeth of the great herbivorous reptile, and repeating 

 the peculiar form of the fore part of the mandible which has been recognized in previously 

 described and figured specimens of that bone.^ Though dislocated, displaced, and some- 

 what scattered in the matrix, they impressed the discoverer with the conviction or certainty 

 of their being parts of the skeleton of the same individual. A comparison of all the 

 bones and fragments of bone submitted to me for determination give no indication of 

 their having belonged to more than one animal, and all are referable to an individual of 

 the same age and size. 



The left radius and ulna are in the best state of preservation ; the right radius and 

 ulna are less entire ; an os cuneiforme is recognizable in the carpal series, and there are 

 metacarpals and a few phalanges of both right and left paws. 



The radius is chiefly remarkable for its powerful spinous or spur-like appendage. 



The antibrachial bones in the present collection confirm the ascription to ' radius ' 

 and ' ulna ' of the two bones imbedded near the upper corner, opposite the right hand, 

 of the great slab of the ' Maidstone Iguanodon ;' " but Mr. Beckles' specimens having 

 been worked out of the less intractable matrix — the Wealden clay — show the configuration 

 and characters of the surface of the entire bone. 



In the following description the surface or aspect of the bone corresponding with the 

 olecranon and ' back ' of the hand is termed ' ancoual ;' the opposite surface, or that 

 answering to the ' palm ' of the hand, is termed ' thenal ;' the surface toward that 

 side of the forearm where lies the radius is termed 'radial;' towards the opposite side 

 ' ulnar.' ' Proximal ' and ' distal ' imply the ends of the bone respectively next to or 

 farthest from the trunk of the animal. 



Ulna. Plate 46, 55. 



The ulna is 1 foot 5^ inches in length ; ' 4 inches 8 lines across the radio-humeral 

 articulation (at a, h, fig. 1) ; 3 inches 8 lines across the distal end; 2 inches 10 lines 

 being the greatest diameter of the middle of the shaft. 



The olecranon (c, fig. 1) extends 1 inch 9 lines above the humeral articular cavity 

 {d, d') ; it is obtuse, about 2 inches thick at the base, thence gradually contracting, to be 

 continued into the ridge {a, fig. 1) extending along or forming the ulnar border of the 



1 More especially in the portion of the mandible of a young Iguanodon (' Binosauria,' PI. 16). 



- ' Dinbsauria,' Pis. 1 and 2. "The radius and ulna lie with their proximal ends ne.xt the right hand 

 upper corner, the latter being distinguished by its prominent olecranon, which is rounded as in the Great 

 Monitor," p. 266. 



^ The length of the ulna in the Maidstone Iguanodon is estimated at 1 foot 6 inches, p. 268. 



r^ 



