SIWALIK AND NARBADA EQUID.E. 15-81 
Species 2. Hippothebium theobaldi, nobis. 
Synonyms — E quus primigenitjs, Meyer, Sivalhippus theobaldi, nobis. 
History. — -As stated in the introduction, certain remains of this species were 
originally described, 1 as belonging to a new genus, under the name of Sivalhippus 
theobaldi. It was, however, subsequently discovered 2 that the teeth on which this 
new genus had been founded, in place of being premolars, as was originally consi- 
dered to be the case, were really milk-molars, and were then seen to belong to 
Hippotherium. It was added in the same notice that certain teeth described by 
H. von Meyer 3 from India, as belonging to H. gracile , should be referred to the 
new species under the name of H. theobaldi. It may be added that this determina- 
tion was made under the erroneous impression that von Meyer had intended to 
distinguish the teeth in question from H. antilopinum, whereas he had intended to 
unite that species with H. gracile. The distinctness of this species rests solely on 
the characters of the upper milk-molars, the true molars, which are referred to it, 
presenting no characters, except then larger size, by which they can be sufficiently 
distinguished from those of H. antilopinum , and, as far as I can judge, closely 
resembling the corresponding teeth of the larger variety of H. gracile. 
Upper milk-molars . — The teeth of the specimen on which the species was 
originally founded are represented in figure 4 of plate XI. The specimen was 
obtained by Mr. Theobald from the Siwaliks of the village of Kaipar, in the Punjab. 
It consists of a fragmentary portion of the left maxilla, containing three complete 
teeth (mm. 2, mm. 3, mm. 4) and the broken base of a smaller anterior tooth 
(mm. 1). To the rear of the last tooth (mm. 4) there is seen the alveolus of a fifth 
tooth, which had not come into use at the death of the animal : this shows that the 
existing teeth belong to the milk-molar series. Erom the isolation of the anterior 
4 pillars ’ of the molars the specimen must be referred to Hippotherium, while from 
the great difference in the form of these teeth from the upper milk-molars of H. 
antilopinum, drawn in figure 2 of the same plate, it is inferred that they must be 
assigned to a second Indian species of the genus, which it has been proposed to call 
H. theobaldi. 
The teeth belonged to a very young colt, as they are but slightly touched by 
wear. In spite, however, of the very small degree of attrition of these teeth, the 
first true molar had cut the gum, as is shown by the condition of its alveolus. This 
unusually early appearance of this tooth seems to distinguish this jaw from the 
jaws of all other horses. 
The first tooth was small and sub-cylindrical. The remaining teeth are oblong 
in shape (the second milk-molar being produced into the usual angle), and, thereby, 
seem to be distinguished from those of other species of the genus, which are more 
• R. G. S. I.,’ Vol. x, P . 31. 
2 Ibid, p. 82. 
3 “ Palaontographica,” Vol. XV, p. 17. 
