ROOM III. HIND FEET OF THE IGUANODON. 297 



to two phalangeals in this Case (the one is a cast of a bone 

 in the Maidstone fossil), which are remarkably abbreviated ; 

 these are probably median phalanges, but their position in 

 the series is not shown in any specimen that has come under 

 my notice. 



Unguals, or distal phalangeals. Wall-case C, Lowermost 

 compartment. The ungual bones, or those which constituted 

 the nail or claw, and were covered by a horny integument, 

 are very large, depressed, and broad above, with two deep 

 curved lateral grooves with rounded margins, which are 

 often impressed with vascular furrows. The proximal end 

 has a transverse, irregularly elliptical, shallow depression, for 

 articulation with the penultimate phalangeal. Lign. 63, fig. 6, 

 is the outline of an ungual bone of the hind foot from the 

 Maidstone specimen, and shows the broad margins sepa- 

 rated from the median convexity by the deep vascular 

 lateral furrows. 



There is considerable variation in the convexity of the un- 

 gual bones, and in its direction ; in some instances, it is 

 nearly straight, and the lateral lobes are symmetrical ; other 

 examples are twisted obliquely outwards, and the furrows 

 are partially obliterated. These differences, doubtless, have 

 relation to the respective toes to which these phalanges 

 belonged. The straight unguals are probably those of the 

 middle toes; those with the oblique outward curve may have 

 belonged to the outer or inner toes. The largest specimens of 

 the ungual bones I have seen are five inches in length, three 

 in breadth, and two in height at the proximal end. 



The following are the respective lengths of a consecutive 

 series of phalangeals in the collection of S. H. Beckles, Esq. : 



Metatarsal 8 inches. 



Proximal phalangeal .... 4^ 



Second phalangeal 3 



Ungual, or distal phalangeal . 5 



On the shelf in the lowest compartment of this Case, there 

 is a fine ungual bone, 4J inches in length, from Tilgate 

 Forest, (No. 384,) with the characteristic lateral furrows ; this 

 specimen was imbedded in a block of the most compact Til- 

 gate grit, and was extracted with great difficulty : hence the 

 roughness of the surface occasioned by the chisel in clearing 

 the bone from its matrix. 



