1891.] ON A MAMMALIAN TOOTH FROM THE WEALDEN. 585 



5. On a Mammalian Tooth from the Wealden Formation 

 of Hastings. By A. Smith WoodwarDj F.Z.S. 



[Eeceiyed 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 Euro- 

 pean Cretaceous Mammal. The specimen is merely a detached tooth, 

 but quite sufiicient 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. PlagiaMlax clawsoni, sp. uov. ; inner (A) and coronal aspect (B) of [? second 

 left lower] niolcar, 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 display- 

 ing the coronal aspect. It has been extricated from the matrix as 



