318 Geological Society. 



At the upper part of the tooth a thin layer of enamel*, besides a 

 coating of cement, is inflected at each groove towards the centre of 

 the dentine ; but about the middle of the tooth the enamel disap- 

 pears, and the convolutions consist of interblended layers of cement 

 and dentine. Thus, on the supposition that the tooth of the Laby- 

 rinthodon of the German Keuper be capped with enamel, its extent 

 must be less than in the tooth of the Warwick sandstone. 



The inflected folds are continued for a greater relative distance 

 before the lateral inflections commence than in the German species, 

 and the anfractuosities are fewer in number, and some of the folds 

 are reflected backwards from near the central pulp-cavity for a short 

 distance before they terminate. 



The modifications of the complex diverging plates of the dentine 

 hardly exceed those of a specific character, and the dentine itself is 

 composed of calcigerous tubes of the same relative size and dispo- 

 sition as in the Labyrinthodon Jaegeri. 



In a section taken from the middle of a smaller and relatively 

 broader and shorter conical tooth from the Warwick sandstone, Mr. 

 Owen found that the anfractuosities were more complicated, with 

 numerous secondary and tertiary foldings, and the external layer 

 of cement was relatively thicker than in the Lab. Jaegeri. 



The generic identity of the Reptiles, indicated by the teeth from 

 the Warwick sandstones, with the Mastodonsaurus of the German 

 Keuper, Mr. Owen believes to be fully established by the concord- 

 ance of their peculiar dental structure above described. And in con- 

 clusion, he says, if, on the one hand, geology has in this instance 

 really derived any essential aid from minute anatomy, on the other 

 hand, in no instance has the comparative anatomist been more in- 

 debted to geology than for the fossils which have revealed the most 

 singular and complicated modification of dental structure hitherto 

 known ; and of which not the slightest conception could have been 

 gained from an investigation, however close and extensive, of the 

 teeth of existing animals. 



A paper was next read, entitled " Observations relative to the 

 Elevation of Land on the shores of Waterford Haven during the 

 Human Period, and on the Geological Structure of the District," 

 by Thomas Austin, Esq. 



The shore on the west side of Waterford Haven, from the rock of 

 Passage to Woodstown, a distance of three miles, presents an almost 

 uninterrupted cliff of clay and gravel, composed chiefly, if not wholly, 

 of detritus of old red sandstone, and enclosing a bed from one to 

 four feet thick of Cardium edule, with other marine testacea of exist- 

 ing species, and a few land-shells. This bed of shells is not con- 

 fined exclusively to the coast, but it extends inwards to the distance 

 of eight miles, distinct traces of it occurring between Waterford and 

 Tramore, and at several intermediate points. In the alluvial valley 

 of Woodstown, close to Newtown Head, the shells rest on an ancient 



* Mr. Owen has subsequently ascertained that this is not true enamel, 

 but a layer of firm dentine, separated from the rest by a thin stratum of 

 fine calcigerous cells. 



