82—16 INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
nearly square in shape; 1 and in which respect they resemble the milk-molars of the 
genus Equus. 
The points distinguishing these teeth from the corresponding teeth of Eippo- 
therium cmtilopinum will he best exhibited by a comparison of the two series. In 
the following table the dimensions of the specimen under consideration are given 
in the first column, and those of the corresponding teeth of E. antilopinum in the 
second. 
Length of three last milk-molars 
„ „ first milk-molar 
Width „ „ „ „ 
Length „ second „ „ 
Width „ „ „ 
Length „ third „ „ 
Width „ „ 
Length „ fourth „ „ 
Width „ „ „ 
. 4-0 3'52 
. 0-32 0-48 
. ... 0-32 
. 1-55 1-42 
. 0-98 0-89 
. L28 1-01 
. 0-96 0-94 
. 1-30 1-1 
. 0-97 0-94 
These dimensions show the much greater proportionate length of the milk-molars 
of the former species. The other differences are the following. 
In H. antilopinum , the anterior £ pillar ’ is sub-cylindrical, and completely en- 
closed by cement in the mass of the crown : the posterior 4 pillar ’ does not extend 
backwards as far as the hinder border of the crown ; while in the second milk- 
molar the same 4 pillar ’ is disconnected from the body of the tooth. The enamel 
is much plicated, and the cement of great thickness. 
In E. theobaldi, on the other hand, the anterior 4 pillar ’ is much compressed, 
so as to be longitudinally elongated ; it also stands out distinctly from the crown, 
so that its posterior border forms a free sharp edge : the posterior e pillar ’ extends 
backwards as far as the hinder border of the crown ; while in the second milk- 
molar the same 4 pillar ’ is united with the adjacent 4 crescent.’ The enamel is but 
slightly plicated, and the cement thin. 
These points of distinction appear to me so marked as to preclude all idea of 
referring the two specimens to the same species. It may be noticed that in nearly 
all the points in which the milk-molars of H. theobaldi differ from those of IE. an- 
tilopinum (and also from those of II. gracile ) they approach the characters of the 
corresponding teeth of Equus. It will be observed that 4 sprigs ’ of enamel jut 
forth from the space between the two 4 crescents' very close to the anterior ‘pillar,’ 
foreshadowing the connection which exists in Equus. 
The milk -molars of H. gracile , as has been noted above, are so like those of 
E. antilopinum , that we have found very few points of distinction : hence tlie milk- 
molars of E. theobaldi will differ from those of E. gracile in much the same points 
as they do from those of E. antilopinum. According to M. Gaudry’s figure of the 
milk-molars of E. gracile , these teeth seem to be slightly more elongated than those 
of E. antilopinum , and are therefore intermediate between the latter and those of 
1 Vide plate XI, fig. 2, and plate V fig. 7, of “ Auimaux Fossiles du Mont Leberon.” 
