162 



MR. E. LYDEKKER ON A MOLAR OF A PLIOCENE EQTTTJS. 



and is in a comparatively early stage of wear. The small antero- 

 posterior diameter of the anterior inner pillar (e), and especially the 

 slight production of the part of this pillar placed posteriorly to the 

 " neck," or point of junction with the main body of the crown, indi- 

 cates that the specimen does not belong to any of the later Pleistocene 

 or recent species of the genus, but to that more generalized group 

 comprising E. sivalensis of the Pliocene of India, and E. Stenonis of 

 the Upper Pliocene of the Yal d'Arno and Algeria and of the Norfolk 

 Forest-bed*. With regard to the upper cheek-teeth of those two 

 forms, which Dr. Forsyth-Major f regards as identical, it appears that 

 in the former the crown-surface of the antero-internal pillar is on the 

 average decidedly more elongated than in the latter J, and that it 

 has a greater tendency to the production of its anterior extremity 

 in advance of the " neck," in which respects it makes an approach to 

 E. quaggoides, F.-Major §, and is thereby connected with the recent 

 species of the genus. Now in the form and connexions of the 

 pillar in question the Nubian tooth agrees so exactly with the 

 Indian species (being, indeed, absolutely un distinguish able from the 

 first true molar of the maxilla of the opposite side represented in 

 pi. xiv. fig. 2 of the ' Palseontologia Indica/ ser. 10, vol. ii.) that, 

 if found in India, it would be unhesitatingly referred to that 

 species. 



When, however, we call to mind the apparent impossibility of 

 distinguishing many of the existing species of the genus by their 

 teeth alone, it would be rash to say that the Nubian fossil belonged 

 to E. sivalensis ; and it will accordingly be advisable to regard it 

 as apparently indicating the occurrence in that region of a species 

 belonging to the same group, and also as affording pretty conclusive 

 evidence that the ossiferous beds of Wadi Haifa, and probably, 

 therefore, those of Kalabshi, are either of Lowest Pleistocene or of 

 Upper Pliocene age, since this group of horses, both in Europe and 

 Algeria, and in India is unknown after the period of the Norfolk 

 Porest-bed, which is either lowest Pleistocene or highest Pliocene. 



The specimen is, however, of interest from another point of view. 

 I have previously expressed an opinion |j that the modern African 

 genera, found in the Pliocene of India, may have reached Africa by 

 way of the Gulf of Aden ; and it is therefore of especial interest to 

 find in the Tertiary of Nubia a member of the primitive 4group of 

 the genus Equus, which is apparently more nearly allied to the 

 Siwalik than to the European species. The occurrence of Hippo- 

 potamus amphibius in the same deposits indicates, however, that the 

 early fauna of this part of Africa was also connected with that of 

 Pliocene and Pleistocene Europe, although this connexion was, 

 perhaps, not so close as in Algeria, where we find in the Pliocene 



* See < Cat. Foss. Mamm. Brit. Mus.' pt. iii. p. 71 (1886). 

 t Quart. Journ. Geol. Soc. vol. xli. p. 2 (1885). 



| Compare the figures given by the writer in the ' Palaeontologia Indica.' 

 ser. 10, vol. ii. pi. xiv., with those given by Forsyth-Major in his " Greschichte 

 der fossilen Pferde, etc." (Abh. schwz. pal. Ges.), pis. i., ii. 



§ Op. cit. pi. ii. fig. 1. 



|| Quart. Journ. G-eol. Soc. vol. xlii. p. 175 (1886). 



