WEALDEN DINOSAURS. 529 



the jaw, the sculptured surface of the crowu 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, 

 subcircuku- 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 (PI. 00, fig. 1 7, 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 

 it bends in from its broadest part, are conspicuous. Minute, short, irregular, longi- 

 tudinal, linear risings of the enamel may be seen with the pocket lens in part of the 

 interspaces of the longer and plainer ridges. The crown expands to its extreme fore- 

 and-aft breadth about one third of its length from the fang. 



The enamel on the inner side of the crown (ili. fig. 15, magn.) begins by a like 

 definite rise from the level of the fang, but this runs straighter across before bending up 

 to the margins of the expanding basal part of the crown. The continuation to the hinder 

 border is more prominent and its termination is more abrupt, giving a slightly angular 

 contour to that border, and making the surface of the crown between the border-ridge and 

 the primary longitudinal ridge a little concave transversely. The basal rising subsides more 

 quickly and completely upon the anterior border, which describes a gentle convex curve, and 

 does not rise so as to render the inner surface of the crown between it and the primary 

 ridge concave. Thus, the inner and outer sides of the crown being determinable by their 

 difference of sculpturing, the fore and hind borders are shown by the above specified 

 characters, and the detached tooth can be referred, as in the case of those of the larger I^ua- 

 nodon, by like characters to its own ramus or side of the jaw ; this, in the present tooth, 

 is the right one. The inner side of the crown of this tooth of lyuanodon Foxii, as in the 

 lower teeth in situ, has one chief median primary longitudinal ridge, increasing in strength 

 from its origin at the basal rising of the enamel to the apex of the crown. On the front 

 facet a short secondary ridge begins, next the primary one, near the apex of the crown, and 

 terminates in the point or ' serration ' next to that of the primary ridge. Another secondary 

 ridge begins at the base of the crown, and runs nearly parallel with the primary one. 

 The margin of the crown, anterior to this ridge, shows the usual smaller serrations. On 

 the hind facet two secondary ridges commence at the up-bent part of the basal one, run 

 parallel with the primary ridge, gaining in prominence and breadth, and terminate in the 



