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Show 1891.] ON A MAMMALIAN TOOTH FROM THE WEALDEN. 585 5. On a Mammalian Tooth from the Wealden Formation of Hastings. By A. SMITH W O O D W A R D , F.Z.S. [Eeceived November 17, 1891.] The estuarine conditions under which the Lower Cretaceous Wealden Formation was deposited are precisely such as have favoured the preservation of so many mammalian remains in several of the Tertiary strata. The existence of Mesozoic Mammalia being well ascertained, it is thus somewhat remarkable that no trace of the Class has hitherto been recorded from any locality in the great area of S.E. England and W . Europe occupied by the fossiliferous sands and clays of the Wealden period. In the underlying Purbeck Beds, it is true, mammalian remains have only been met with in one thin stratum in the cliffs of Durdlestone Bay, notwithstanding the fact that this series of rocks is likewise in great part of estuarine origin. However, in all cases in which Mesozoic Mammalia have been discovered, whether in Europe or America, they are invariably restricted to certain definite thin layers or to irregular accumulations of the debris of plants and Vertebrata ("bone-beds") of local occurrence and limited extent. One of these irregular bone-beds in the Wadhurst Clay of the Wealden Formation has at last yielded the first evidence of a European Cretaceous Mammal. The specimen is merely a detached tooth, but quite sufficient for recognition. It was discovered by Mr. Charles Dawson, of Uckfield, in an irregular mass of comminuted fish- and reptile-bones, with scales and teeth, occurring in lenticular patches at one definite horizon in a quarry near Hastings. Mr. Dawson has for a long period been engaged in a careful examination of the deposit, Fig. 1. Fig. 2. Fig. 1. Plagiaulax dawsoni, sp. nov.; inner (A) and coronal aspect (B) of [? second left lower] molar, four times nat. size.-Wealden (Wadhurst Clay), Hastings. Fig. 2. Plagiaulax minor; coronal aspect of right lower molar 2 (not reversed in drawing), eight times nat. size.-Middle Purbeck, Durdlestone Bay. and this is the first fossil met with presenting sufficient resemblance to a mammalian tooth to seem worthy of forwarding to the British Museum for special determination. The tooth in question is shown of four times the natural size in the accompanying woodcut (fig. 1), A being the side view, and B displaying the coronal aspect. It has been extricated from the matrix as |
