CUNICULAB, OB RABBIT-LIKE HYBACOTHEBE. 425 



by comparing figures 170 and 171 with the corresponding 

 molars of the Hyracoiherium leporinum, (fig. 167). The 

 true molars of these two species further differ in a point not 

 explicable on the supposition of their having belonged to 

 individuals or varieties differing merely in size, for the 

 ridge which passes transversely from the inner to the outer 

 cusp is developed midway into a small crateriform tubercle 

 in the teeth of the Hyracoiherium leporinum, but preserves 

 its trenchant character in the Hyrac. Cuniculus, even in 

 molars which have the larger tubercles worn down. 



The premolar, or false molar (fig. 171), in the series of 

 detached teeth from Kyson, which is either the third or 

 fourth, presents the same complication of the crown which 

 distinguishes the Hyracotherlum from the Chceropotamus, 

 but with the same minor modification which distinguishes 

 the true molars of the Kyson species from those of the 

 Hyrac. leporinum of Herne Bay; i. e., the two ridges 

 which converge from the two outer tubercles towards the 

 internal tubercle are not developed midway into the small 

 excavated tubercle, as in the Hyrac. leporinum, but are 

 simple. The disparity of size between the true and false 

 molars appears to be greater in the Hyrac. Gunlculus than 

 in the Hyrac. leporinum. 



This discovery of a second species of the genus Hyra- 

 cotherium, associated with fossil vertebrae of a Serpent, in 

 the Kyson sand, tends to place beyond doubt the equiva- 

 lency of that formation with the eocene deposits at the 

 estuary of the Thames, and corroborates the inference de- 

 ducible from the mammalian, ornithic, and ophidian re- 

 mains of the London clay, that it was deposited in the near 

 neighbourhood of dry land. 



