392 SOLIPEDIA. 
PACHYDERMATA. SOLIPEDIA. 
Fig. 152. 
Ist upper molar, nat. size, Hquus lst upper molar, nat. size, Hguus 
caballus. plicidens, Oreston. 
FOSSIL HORSE, wirn THE ENAMEL-FOLDS OF THE MOLAR 
TEETH PLicaTED. (Hquus plicidens.) 
Amonest the numerous teeth of a species of Hquus, as 
large as a horse fourteen hands and a half’ high, collected 
from the Oreston cavernous fissures, I have found specimens 
clearly indicating two distinct species, so far as specific 
differences may be founded on well-marked modifications of 
the teeth. 
One of these, like the ordinary Equus fossilis of the drift 
and pleistocene formations, differs from the existing Lqwus 
caballus by the minor transverse diameter of the molar 
teeth, and is noticed in the preceding section; the other, 
in the more complex and elegant plication of the enamel, 
and in the bilobed posterior termination of the grinding 
surface of the last upper molar, more closely approximates 
to the extinct Horse of the miocene period, which M. H. 
v. Meyer has characterised under the name of the Hquus 
caballus primigenius.* The Oreston remains differ, how- 
* * Nova Acta Acad. Nat. Curios.’ tom. xvi. p. 448. 
