70 ANCHITHERIUM. 
The surface, for attachment of the external pterygoid muscle in advance inter- 
nally of the glenoid articulation, is much less inclined than in the Horse; and at 
the antero-internal part, as in this, it presents a foramen conducting to the fora- 
mina rotundum and spheno-orbitale. 
The latter, and the optic foramina, are of large size, and hold very nearly the 
same relative position as in the Horse. 
The interpalatine notch, as in the latter, expands as it approaches its bottom, 
which is on a line with the interval of the fifth and sixth molar teeth. 
The hard palate is broken in the specimen, but it appears to have been about as 
much arched as in the Horse, and the exit of the posterior palatine canals is just 
in advance of the sides of the interpalatine notch. 
Inferior Maxilla.—(P1. X., Figs. 18,19; XI. 5,6.) As in the case of the alveoli of 
upper jaw, corresponding with the shortness of the teeth relatively and compara- 
tively with those of the Horse, the body of the lower jaw of Anchitherium is 
proportionately less deep than in the latter. Its outer side is vertical and slightly 
convex; its base is thick and slightly convex forward; and its upper margin 
rapidly ascends posteriorly, and curves in a sigmoid manner more backward to the 
summit of the coronoid process than in the Horse. 
The coronoid process is curved like in ordinary ruminants, but is relatively 
shorter and broader. 
The condyle is very like that of the Horse, but the notch in advance of it is 
relatively broader. 
The ramus, which in the Horse is very slightly depressed externally below the 
position of the coronoid process, in the fossil is almost as much depressed as in the 
Peccary. 
Dentition.—(Pl. X. 14-17, 21; XI. 1, 3-8.) Gervais! states the formula of the 
dentition of Anchitheriwm to be:— 
3 8 Ee te we 
— Can. — mol. - 
9 9 7 
3 3) ST! a 
mM. 
It is extraordinary that Anchitherium should be so much like Palaeotherium in 
the anatomical and physiological construction of its teeth, and yet be so much like 
the Horse in its skeleton. 
The crowns of the molar teeth of Anchitherium are entirely devoid of cementum, 
and in the adult are completely exserted. 
The specimens of Anchitherium Bairdii, which we have an opportunity of 
examining, contain in the upper and lower jaws all the molar teeth except the 
first of the series. 
The posterior six upper molars (XI. 3, 4,) are nearly alike in form and size; the 
crowns, as in those of Pulaeotherium, consisting of two transverse pairs of lobes. 
The outer lobes, as in the genus just mentioned, are demiconoidal with triangular 
summits, the basal angles of which are continuous with the extremities of inverted 
U shaped ridges bounding the sides and bases of the external transversely concave 
surfaces. 
The inner lobes are conoidal, and are prolonged outwardly to the antero-internal 
* Zoolog. et Palzont. Frane., p. 63. 
