Geological Society. 61 



ai'e 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 tertiar}' 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 

 band, 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 by C. Lyell, Esq., F.G.S., was afterwards read, " On the 

 Fresliwater Fossil Fishes of Mundesley, as determined by M. 

 Agassiz." 



In a memoir on the boulder formation and associated freshwater 

 deposits of Eastern Norfolk*, Mr. Lyell stated, on the authority of 

 Mr. Yarrell and the Rev. L. Jenyns, that the scales and teeth of fishes 

 which had been then procured in the fluviatile beds of Mundesley 

 belonged to the Esox lucius, to a trout or an undeterminable species 

 of Sahno, to a carp, probably the Cyprinus carpio, and to a distinct 

 species of Perca. 



This collection, with some additions recently sent to the author 

 by Mr. Wigham, was examined by M. Agassiz during his late visit 

 to England. The decision of Mr. Jenyns with respect to the distinct- 

 ness of the perch, M. Agassiz fully confirmed ; but he was of opinion 

 that the pike differs from the Esox lucius, and that the supposed carp 

 is a species of Leuciscus ; and that the trout is not truly a trout, al- 

 though one of the same great family. 



From this examination, therefore, Mr. Lyell says it is apparent that 

 these remains belong to species not identical with any European 

 freshwater fishes hitherto described; but that they nevertheless be- 

 long to an ichthyological fauna, more modern and more nearly re- 

 sembling the recent than any other with which M. Agassiz is ac- 

 quainted in a fossil state. 



Similar remains have been found by Mr. Lyell at Runton, near 



» See Proceedings, ante, p. 171. 



