278 DE. A. S. WOODWAKD ON SOME MAMMALIAN [May I9II, 



9. On some Mammalian Teeth from the Wealden of Hastings. By 

 Aethue Smith Woodward, LL.D., F.R.S., E.L.S., Sec.G.S. 

 (Read March 22nd, 1911.) 



Since the late Prof. Marsh's discovery of mammalian teeth and 

 bones in the coarse grits of the Laramie Formation in Wyoming 

 (U.S.A.), Mr. Charles Dawson, F.G.S., has persistently searched for 

 similar fossils in deposits of the same nature in the Wealden 

 formation of Sussex. These beds consist chiefly of coarse quartz- 

 grains mingled with teeth of fishes and fragments of bones, and 

 were originally noticed by Man tell under the name of 'Tilgate 

 Grit.' According to Mr. Dawson's observations, however, they 

 form only small lenticular deposits, and occur at several horizons 

 in the Wealden Series. 



The first result of this search was the discovery of a molar of 

 PlagiaulcLV, which I described and named PI. dawsoni in 1891. l 

 More recent work, in which Mr. Dawson has been helped by Messrs. 

 P. Teilhard de Chardin and Felix Pelletier, has led to the finding of 

 three additional specimens — two probably belonging to Plagiaulax 

 itself, the third to a distinct though related genus. The first- 

 described tooth was met with in the Wadhurst Clay behind 

 St. Leonards, while the three new teeth were obtained from the 

 Ashdown Sands of the Fairlight Cliffs near Hastings. 



The two new molars which seem to belong to Plagiaulax are 

 unfortunately very imperfect. In one the crown is seen to «be 

 closely similar to that of the original tooth of PI. dawsoni. In the 

 second specimen most of the crown has decayed, but the two 

 divergent roots are well displayed, the one somewhat stouter than 

 the other. 



The third specimen is especially well preserved, and exhibits the 

 whole of the crown, as shown in the accompanying text-figure 

 (p. 279). It is a molar somewhat longer than wide, with nearly 

 parallel sides and one end truncated a little obliquely, while the other 

 is gently rounded : its total length does not exceed 2 millimetres. 

 The crown is covered with dense smooth enamel, without any traces 

 of wear, and so displays the exact shape and proportions of all the 

 cusps. It is marked by a median longitudinal depression, which 

 widens into a narrow flattened lip at the ( rounded end. On either 

 side of the median depression is a row of three blunt eusps, of 

 which those at the apparently internal border are the higher. 

 The latter cusps are obtusely conical, the two at the rounded end 

 being in close connexion, while the third at the truncated end is 

 somewhat larger and well separated from the others by a cleft. 

 The low external cusps approach a transversely-crescentic shape, 



i ' On a Mammalian Tooth from the Wealden Formation of Hastings ' Proc. 

 Zool. Soc. 1891 (1892) pp. 585-86. A tooth of doubtful origin was subse- 

 quently described by Mr. E. Lydekker, ' On a Mammalian Incisor from the 

 Wealden of Hastings ' Q. J. G. IS. vol. xlix (1893) pp. 281, 282. 



