EQUIDM. 51 



are three digits in each foot, with the apparent exception of H. an- 

 tilopinum, in which they appear reduced to one. 



There are two cavities on the surface of the maxilla, the second of 

 which corresponds to the "larmier " of the ruminant Artiodactyla. 

 The accompanying woodcut (fig. 11) shows the structure of the 

 upper cheek-teeth in an undetermined Indian species. The number 

 of digits apparently varies from one to three. 



Hipparion gracile (Kaup 1 ). 



Syn. Equus (Hippotheriuni) gratilis, Kaup 2 . 

 Equus (Hippotheriuni) nanus, Kaup 3 . 

 Equus primigenius, Meyer 4 . 

 Equus angustidens, Meyer 5 . 

 Hipparion diplostylum, Gervais 6 . 

 Hipparion prostylum, Gervais 7 . 

 Hipparion mesostylum, Gervais 8 . 

 Hipparion mediterraneum, Hensel 9 . 

 Hipparon brachypus, Hensel 10 . 



According to Gaudry, 'Animaux Fossiles du Mont Leberon,' pp. 32- 

 33, the above-mentioned forms are in all probability specifically 

 the same ; although individual specimens of the bones and teeth 

 present a great variation in size. This difference, coupled with 

 the extreme difficulty of distinguishing many of the recent Equidce 

 by their teeth and bones alone (see page 73), suggests, however, 

 the possibility of there being more than one European species of the 

 present genus. H. von Meyer's names have the priority over Kaup's, 

 but the latter is too generally accepted to admit of supersession. 

 This is the type species, and has three digits to each foot. 



Hob, Europe, North-western Persia 11 , and Algeria 12 . 



1 Neues Jahrb. 1833, p. 327 ; Equus (Hippotherium). 



2 Lftc. cit. 3 Loc. cit. 

 * Zeitschr. fur Min. 1829, vol. i. p. 152. 



5 Ibid. p. 280. 



8 Comptes Eendus, vol. xxix. p. 285 (1849). 



7 Loc. cit. 8 Loc. cit. 



9 Monatsb. k. preuss. Ak. Wiss. 1860, p. 356 (1861). 



10 Ibid. 1862, p. 560 (1863). 



11 See a paper by the present writer on Persian Mammals in the Quart. 

 Journ. Geol. Soc. TO! xlii. (1886). 



12 Thomas. Mem. Soc. Geol. France, ser. 3, vol. iii. art. 2, pi. viii. (ii.) 

 (1884). 



B2 



