﻿WEALDEN FORMATIONS. 



13 



of the 'Monograph' on the Iguanodon of Pal. vol. issued for year 1854, and also "a 

 distal phalanx of one of the toes." " I cannot tell/' writes Mr. Fox, " where I have the 

 bone itself, but its shape is exactly like that in Iguanodon Mantetti, very little curved in a 

 downward direction, and rather broad. 1 In the little paper box, along with the fragment 

 of jaw, you will find one very small tooth, quite perfect, 2 that came out of this slab in 

 dressing." 3 This slab was found in the fallen cliff, about 150 

 yards east of " Barnes High," directly fronting the den of my 

 Polacanthus, which I dare say you will remember seeing. The 

 skull and broken jaw were found about 60 yards further 

 eastward." 4 



In the accompanying Woodcut, fig. 2, of the caudal vertebra, 

 nat. size, of Iguanodon Foxii, are added letters of reference corre- 

 sponding with those on the figure of a caudal vertebra of Igua- 

 nodon Mantetti above quoted. The anterior or cervical vertebrae 

 show the modification • of the front ball and hind cup (' Monogr. 

 on Wealden and Purbeck Dinosauria,' Part II, 1855, Tab. I, 

 figs. 3, 4). If the sacral vertebrae should show the broad under 

 surface, as in s 4, Tab. Ill, Monogr. ext., a corresponding variability of vertebral shape in 

 the same skeleton will characterise the present small kind of Iguanodon as it does the 

 large kind. 



The tooth (PI. II, fig. 12) is 5 lines in length in a straight line ; it is moderately curved, 

 with the convexity (as the teeth in sifu above described show) towards the inner surface of 

 the jaw, the sculptured surface of the crown having the same aspect. The length of the 

 fang is 3 lines, that of the crown is 2 lines, but the apex of this has been broken 

 off. The breadth of the crown is 2f lines ; the thickness of its base 1| lines. 

 The fang tapers to its implanted end, which is hollow and filled with matrix, 

 subcircular in form, \ a line in diameter ; the dentinal wall is here very thin. The fang 

 expands towards the crown, chiefly in the antero-posterior direction, and is shorter on 

 the outer concave than on the inner convex side, the coronal enamel descending rather 

 lower on the outer side. The inner side of the fang is broader and less convex across 

 than the outer side, towards which the fang seems to be, as it were, rather pinched in. 



The outer side of the crown (ib., fig. 17, magn.) begins with a feeble rise of the enamel 

 from the level of the fang, such rise describing a slight convexity downward ; this side of 

 the crown is gently concave lengthwise, more strongly convex across ; it is relieved by 

 low ridges continued down from the apices of the chief serrations, most of them subsiding 

 before gaining the basal line. The finer serrations on each margin of the crown, where 



1 The shape and proportions of the ungual phalanges vary in the toes of the fore and hind feet in 

 Iguanodon Mantelli. 



2 Letter received 4th February, 1870. 3 lb. ib. 



4 Letter above cited. The skull and broken jaw are the subjects of figs. 9 and 9 a, of PI. I. 



