114 A. S. Woodward — On a Tooth of Alligator. 



Fig. 9. Lamna crassa (Agassiz) ; tooth, inner {a), outer (J), and lateral (c) aspects. 



Ibid. [P. 5833 «.] 

 Figs. 10-16. Corax pristodontus, Agassiz ; associated series of seven teeth, outer 



aspect. Ibid. [P. 5827.] 

 Fig. 17. Elasmodus Greenonghi, Agassiz; imperfect left mandibular tooth, inner 



aspect. Lower Danian (Poudingue de la Malogne), Ciply. 



[P. 5837.] 

 Fig. 18. Bottosaurus belgicus, sp. noT. ; crown of hinder tooth, coronal {a), external 



or internal {b), anterior or posterior (c), and inferior (d) aspects. 



Lower Danian (Craie brune), Ciply. [E. 1802.] 



Except Fig. 1, all the drawings are of the natural size. The specimens are in 

 the British Museum, and the numbers in square brackets refer to the Eegister of the 

 Geological Department. 



III. — Note on a Tooth of an Extinct Alligator [Bottosaurus 



BELGICUS, sp. nOV.) from THE LoWER DaNIAN OF CiPLY, BELGIUM. 

 By A. Smith Woodward, F.G.S., F.Z.S. 

 (PLATE IIL Fig. 18.) 



AMONG- the vertebrate remains discovered by M. Houzeau de 

 Lehaie in the "Craie brune phosphatee " of Ciply, is the crown 

 of a large tritoral tooth, of unusual form and somewhat difficult of 

 determination. A study of the reptilian teeth from the New Jersey 

 Greensand in the Philadelphia Academy of Sciences has, however, 

 suggested to the writer a plausible explanation of the specimen ; 

 and a brief notice of its characters may perhaps lead to the discovery 

 of more satisfactory evidence of the animal to which it pertains. 



As shown by the figures (PI. III. Figs. 18a-d.), which are of the 

 natural size, the tooth is longer than its maximum breadth, tapering 

 at the extremities, without a longitudinal keel, and covered by dense 

 dark enamel, which is nearly smooth, exhibiting only a faint trans- 

 verse rugosity. Onp extremity of the crown is more elevated than 

 the other, and the median portion is slightly raised above both these 

 points. At each of the three elevations the surface enamel is worn 

 off, thus exposing the softer light-coloured dentine. In basal view 

 (Fig. I8d) the dentine is shown to consist of two or three super- 

 posed cones. 



There being apparently no piscine dentition with which such a 

 tooth can be compared, it is necessary to refer to the Reptilia ; and 

 among these the posterior teeth of the Alligators seem to present the 

 most striking resemblances. In the fossil Alligatoi's of the Lower 

 Tertiaries the short tumid crowns of the hinder teeth are often 

 found detached from the root, while they differ only from the fossil 

 now under discussion in their much smaller size, the absence of 

 lateral eminences, and the presence of at least a short, feeble, 

 longitudinal keel. In a supposed Upper Cretaceous Alligator, how- 

 ever, of which the type species is comparatively large, the posterior 

 teeth agree much more closely both in size and form with the Ciply 

 specimen ; and it seems reasonable to predict, from an examination 

 of this fossil, that good evidence of a member of the Alligator-group 

 will eventually be found in the Upper Senonian or Danian of 

 Western Europe. Bottosaurus, as the imperfectly known genus in 



