Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/132

46 Figures of these teeth, of the natural size, are given in plate 62 A, figs. 4 a & b, of the work cited.

I am at a loss to discover the smallest resemblance between these teeth and either those of Thecodontosaurus of Riley and Stutchbury or the so-called "Palæosaurus" platyodon tooth, which is represented in the same plate, fig. 7; nor can I divine in what sense the Cladyodon teeth can be said to be intermediate between the two. If they were affirmed to be intermediate between Thecodontosaurus and Palæosaurus cylindrodon, the statement would be intelligible, though I do not think it would be altogether accurate.

I have been favoured by Mr. T. G. B. Lloyd, F.G.S., with the opportunity of examining three Saurian teeth from the quarries which yielded Cladyodon. Two of these teeth (Pl. III. fig. 4) are so similar to those of Palæosaurus cylindrodon in form, and even in colour, that I conceive them to belong to the same genus, and perhaps to the same species, although they are twice as large as the teeth from Bristol. They show most distinctly the abrupt cessation of the anterior serrated ridge about halfway down the crown, which beneath this point is rounded and curved as in Megalosaurus. I see no reason to doubt that these are Dinosaurian teeth. Of the other tooth, only the crown, which is 1⋅8 inch long, is preserved (Pl. III. fig. 11). This tooth must have had, as nearly as maybe, the same dimensions as the hindmost tooth in the upper jaw of the Megalosaurus figured in the 'Quarterly Journal' of this Society (vol. xxv. pl. 12); and if placed over that tooth it corresponds with it in contour with remarkable closeness. On the whole, however, the crown of the Megalosaurian tooth is thicker near the fang than the present tooth. But what distinguishes the latter at once from all the Megalosaurian teeth of which I have been able to obtain a sufficiently clear view, is the fact that the serrated anterior ridge extends along the whole length of the crown, instead of stopping short halfway from the apex, as it does in Megalosaurus. In this respect the tooth from the Trias resembles those of Teratosaurus; and it may possibly belong to that genus.

Thus it appears that there are two kinds of Dinosaurian teeth in the Warwickshire Trias—one kind allied to Megalosaurus, the other to Thecodontosaurus.

Thanks to Mr. Kirshaw, who has so skilfully worked out many of the fossils of the Warwickshire Trias, I am able to add new evidence which tends in the same direction. This consists of three consecutive vertebræ (Pl. III. fig. 9), which have been ankylosed together, though they are now separated by the breaking away of the greater part of the hinder portion of the second vertebra. The centra of these vertebræ are much constricted in the middle, while their articular surfaces are flat or slightly excavated (Pl. III. fig. 10). The bones have been so much distorted and crushed that it is hard to say what the contour of these surfaces may have been; but they were either circular or oval, the long axis of the ellipse being vertical. The spinous processes are broken away. The faces of the præzygapophyses look inwards as well as upwards, so as to embrace the postzygapo-