R. Etheridge, jun. — New Carboniferous Fossils. 243 



I had in MS. adopted the name JToplodus; 1 but at the suggestion of 

 Mr. W. Davies, of the British Museum, who was kind enough to 

 assist me in their comparison with specimens of different species of 

 Petalorhynchus in the Museum collection, I have referred them to the 

 latter genus. Independently of the peculiar form and relatively 

 greater development of the posterior face as compared with the 

 anterior, the teeth resemble the genus Petalodus, as well as that 

 to which they are referred, in the cutting edge of the crown, 

 smooth polished surface, and entire and undivided root; but at the 

 same time one of the peculiarly distinctive characters of PetalorJiynchus 

 is not visible — the non-extension of the transverse imbricating folds 

 to the lateral angles of the crown.. 



PetalorJiynchus ? Benniei, sp. nov. PI. VIII. Figs. 3 and 4. 



Sp. chars. — The general outline is somewhat hoof-shaped, with the 

 exposed portion of the tooth consisting of two parts, one, a vertical 

 portion forming the cutting edge of the tooth, the other part, nearly 

 at right angles to this, and from the under surface of which proceeds 

 the undivided root (Fig. 3, r) . The superior margin or cutting edge 

 (Fig. 4, c, c) is convex in outline, minutely crenulate-striate, and with 

 a single, sharp, and central denticle ; the surface of both portions of 

 the tooth is smooth and polished. The anterior face of the vertical 

 portion of the crown is slightly convex, the posterior face concave, 

 and descends lower than the former, to its union with the horizontal 

 portion. The inferior margin of the anterior face of the crown is 

 formed by a ridge, with scarcely any visible imbricating folds or 

 bands, and is unsymmetrical with the superior margin or cutting 

 edge. The horizontal portion of the crown is notched at its free 

 edge, or has a re-entering angle in it. The root proceeds as a single 

 fang from the whole of the under surface of the horizontal portion. 



Obs. — Mr. W. Davies has very kindly afforded me the following 

 information : — A similar tooth formed one of a collection brought 

 under the notice of the Geological Section of the Bradford Meeting of 

 the British Association the year before last (1873) by Mr. W. Home, 

 of Leyburn, from the Yoredale Limestone of Wensley dale, Yorkshire. 3 

 Mr. Davies and Mr. Home had, before the meeting referred to, dis- 

 cussed the probability of this tooth having been the entire dental 

 armature of an upper or lower jaw, or whether it might have been 

 one of several teeth appertaining to the same mouth. Mr. Davies is 

 also much impressed with its resemblance, externally, to the un- 

 covered teeth of the Parrot fishes generally, but more especially to 

 the Diodons ; but, as the fish which bore this tooth was undoubtedly a 

 Selachian, and the structure of the tooth, within the mouth, so dif- 

 ferent to that of the Diodons, it can have no affinity with these 

 recent fishes, although very suggestive of a Selachian with a similar 

 form of mouth. A specimen of P. Benniei is in the British Museum 

 Collection, from Beith, presented by Mr. Craig. 



1 6tt\^], a hoof. 



2 Brit. Assoc. Reports, T. S. p. 84 (short abstract only). — I take this opportunity of 

 expressing my thanks to Mr. Davies for much kind assistance rendered me at the 

 British Museum on several occasions. 



