420 HYRACOTHERIUM. 
from any living Mammalia, and to have had the nearest 
affinity to the Cheropotamus. 
The fossil in question consists of a mutilated cranium 
(fig. 165) rather larger than that of a hare, containing the 
molar teeth of the upper jaw nearly perfect and the sockets 
of the canines. It was discovered in the London clay 
forming the cliffs at Studd Hill, about a mile to the west 
of Herne Bay, by William Richardson, Esq., F.G.S., who 
kindly gave me the opportunity of describing it in the 
Geological Transactions for 1839.* 
The molars are fourteen in number in the upper jaw, and 
resemble more nearly those of the Cheropotamus than the 
molars of any other known genus of existing or extinct 
Mammalia. They consist of four premolars and three true 
molars on each side. The first and second premolars, count- 
ing from before backwards, have simple sub-compressed 
crowns, surmounted by a single median conical cusp, with 
a small anterior and posterior tubercle at the outer side, 
and a ridge along the inner side of its base: they are se- 
parated from each other by an interspace nearly equal to 
the antero-posterior diameter of the first premolar, which 
measures two lines and a half. The second and the rest 
of the series are in close juxtaposition (fig. 166). The 
third and fourth premolars present a sudden increase of 
size and of complexity of the grinding surface, with a cor- 
responding change of form: their grinding surface supports 
three principal tubercles or cusps, two on the outer and 
one on the inner side: there are two smaller elevations, 
with a depression on the summit of each, situated in the 
middle of the crown, and the whole is surrounded by a 
ridge, which is developed into a small cusp at the anterior 
and external angle of the tooth. These teeth form the 
* Geol. Trans., Second Series, vol. vi. p. 203. 
