LOPHIODON MINIMUS. 315 



be a portion of the reserve-socket for the germ of the suc- 

 ceeding molar tooth, of which there is no trace in the fossil. 



The tooth in question must therefore be regarded as 

 a permanent premolar, and as the second in the series ; 

 and the fossil is accordingly proved to belong to a species 

 of LopModon, The premolar (p g) bears the same pro- 

 portion to the true molar (a and 5), as the premolar of 

 the larger species of LopModon exhibits in the entire se- 

 ries of the lower jaw figured by Cuvier in the volume 

 above cited, pi, i. Both teeth in fig. 108 belong to the 

 same side of the lower jaw, most probably to the same 

 lower jaw, and they offer no characters by which they can 

 be distinguished from the LopModon minimus the " tres- 

 petite espece d'Argenton," described by Cuvier in the 

 volume cited at p. 194. 



In the posthumous edition of the ' Ossemens Fossiles, 1 

 8vo. 1834, vol. iii. p. 362, a note is appended to the ar- 

 ticle on the Lophiodons, in which M. de Basterot, " jeune 

 Naturaliste Anglais, 11 is cited as having maintained an 

 opinion in a paper read to the " Societe d'Histoire Na- 

 turelle de Paris, 11 that the freshwater marls in central 

 France, from which the remains of the Lophiodons had 

 been derived, belonged to the formation of the plastic clay 

 and lignite, which immediately succeed the chalk. 



The determination of the LopModon minimus in the 

 plastic clay, overlying the chalk at Bracklesham on the 

 Sussex coast, affords satisfactory confirmation of the high 

 antiquity of the epoch of the tapiroid Pachyderms in the 

 tertiary division of geological time. 



