﻿» 



WEALDEN FORMATIONS. 7 



applied. The outer surface of the deflected ends of the premaxillaries is pitted and finely 

 punctate or rugose. 



The fractured bases of the premaxillary teeth succeeeding the first show a transverse 

 diameter nearly eqnal to the fore-and-aft one, and I can form no judgment as to the 

 shape of their missing crowns, save on the analogy of the Iguanodon. They are close- 

 set, and if those crowns extended antero-posteriorly they must have overlapped. This 

 Iguanodontal arrangement is demonstrated in the undisturbed maxillary teeth, of which 

 eight are recognisable ; the hind border of one crown overlaps the fore border of the 

 tooth behind. 



The two anterior maxillary teeth have slipped in part from their sockets and do not 

 show this arrangement. The first is the smallest antero-posteriorly, but its crown has 

 been worn to the fang, and when entire would be larger in that direction. The second 

 tooth is less worn, and yields in size to the third. In the fifth the full size of the 

 crown, antero-posteriorly, is shown, and this tooth is selected for the magnified view in 

 PL I, fig. 10. 



The outer surface of the crown is bisected by a medial primary longitudinal ridge ; 

 behind this ridge the surface is smooth and concave transversely ; in front of the ridge 

 the similarly concave surface is accentuated by two low secondary longitudinal ridges. 

 The same characters appear, in the degree in which the crown is unworn, in the other 

 maxillary teeth. 



In upper or maxillary molars of Iguanodon Mantetti the following varieties have been 

 recognised and figured. 



In the 'Monograph on the Iguanodon' (Palseontographical Society's volume for 

 1854, issued 1855, PI. XVIII, fig. 2) the primary ridge is nearer the fore border of the 

 crown than in fig. 10, PL I, of the present Monograph; there is a feeble indication of a 

 secondary ridge on the anterior transversely concave facet. There are two secondary 

 ridges in the posterior facet, as in fig. 10, and the crown is so worn down as to show no 

 trace of marginal serrations. 



In the upper tooth, fig. 1, PL XVIII (Monograph cit.), the crown is less worn and 

 the marginal serrations appear beyond the line of extreme breadth. The anterior facet 

 shows no secondary ridge ; the two such ridges in the posterior facet run together in the 

 terminal part of the crown. 



In the 'Monograph on Iguanodon, Supplement No. II' (Pal. Vol. for 1858), 

 « Cretaceous Reptilia," PL VII, fig. 2, three upper molars are shown in situ with 

 the Iguanodontal overlap, viz. the hind border of a fore-tooth ( m ) over the fore-border of 

 the next tooth ( n ) : in these upper molars the primary ridge is sub-medial, and the front 

 face smooth as in fig. 10, PL I, of the present Monograph; the two secondary ridges 

 on the hind facet are feebly indicated. The marginal serrations are shown in the 

 preserved terminal part of the crown, which is entire in the teeth marked n and . 

 Bisect the tooth n at the line at which it is worn away in figs. 9 and 10, PL I, and no 



» 



