SIWALIK AND NARBADA EQUIDiE. 
17—83 
R. theohaldi. The second milk-molar of the latter species agrees with the corres- 
ponding tooth of R. gracile in the union of the posterior ‘ pillar ’ with the adjacent 
‘crescent,’ and differs by the presence of the infold of enamel at the inner side of 
the anterior angle. 
Second specimen. — In a second specimen of the milk-molars of R. theohaldi 
(Indian Museum, No. C. 154) from Niki, containing the two last teeth of that series, 
the essential characters are the same as in the type specimen : the dimensions are 
as follows : — 
1-12 
0 - 87 
1 - 2 
Length of third milk-molar 
Width „ „ 
Length „ fourth „ 
Width „ „ „ 
0'88 
The disproportion between the two diameters is here greater than in the first 
specimen. 
Maxilla of first specimen. — The fragment of the maxilla in which the figured 
teeth are contained is too imperfect to give any idea of the characters of the cranium, 
except the fact that it was furnished with a very large lachrymal depression or 
‘larmier.’ 
Distinctness as a species. — I am unable to find in any of those of the American 
species of Rippotherium of which the milk-molars have been described any close 
resemblance to the teeth described above, and therefore come to the conclusion that 
they are rightly referred to a distinct species. 
Upper true molars. — Seeing that the upper milk-molars have afforded evidence 
of two species of Indian hippotheres, it now remains to discover whether we can 
distinguish between the true molars of these species. In figure 3 of plate XI, there 
are represented four teeth of the left upper permanent molar series of a hippo- 
there from Mr. Theobald’s Niki collection, of somewhat larger dimensions than those 
of R. antilopinum , and also differing slightly in form from those teeth. Since the 
upper milk-molars of R. theohaldi are somewhat larger than those of R . antilopinum, 
it is inferred that the same rule holds good with regard to the true molars, wherefore 
the teeth in question have been assigned to the former species. It may he added 
that if the milk-molars had not been known, it would have been doubtful whether 
the true molars would have afforded ground for the formation of two species. 
The figured specimen consists of a fragment of the left maxilla containing four 
complete teeth, and the alveolus of another tooth on either side of the four remaining 
ones. The second remaining tooth, counting from the left (p. m. 4), is less worn 
than either of the teeth on its two sides, and must accordingly he the last premolar : 
the four teeth will, therefore, he respectivly the third and fourth premolars 
(p. m. 3, p. m. 4), and the first and second true molars. The crowns of the teeth are 
nearly square in cross-section, and the premolars are considerably larger than the 
true molars. The anterior ‘pillars’ are compressed longitudinally, and stand out 
distinctly from the crown : small processes of enamel project from the space 
