CUNICULAR, OR RABBIT-LIKE HYRACOTHERE. 425 
by comparing figures 170 and 171 with the corresponding 
molars of the Hyracotherium 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 differmg 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 Hyracotherium 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 Hyracotherium from the Cheropotamus, 
but with the same minor modification which distinguishes 
the true molars of the Kyson species from those of the 
Hyrac. leporinum of Herne Bay; 7%. ¢., 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. Cuniculus 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- 
leney 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. 
