434 Dr. C. W. Andrews — Fauna of Wadi-Natrun, Egypt. 



Eipparion gracile Kaup, from the Pliocene of Epplesheim. It 

 differs, however, from most specimens of that species in having its 

 inner column more laterally compressed. In the form of the inner 

 column Hipparion Theohaldi, from the Siwalik Hills, approaches 

 the Egyptian form very nearly, some of the teeth figured^ by 

 Mr. Lydekker being almost identical in structure with the specimen 

 here described. In the absence of more complete material it will be 

 best to refer our specimen to the widely spread species Hipparion 

 gracile, at the same time drawing attention to the fact that in some 

 respects it resembles H. Theohaldi, and, like it, probably represents 

 a somewhat later stage in the evolution of the group, the form of 

 the inner column being rather more like that of Equus than is the 

 case in the European species. 



The tooth from Wadi- Haifa described by Lydekker (Quart. Journ. 

 Geol. Soc, vol, xliii, 1887, p. 161) is that of a true Equus, near 

 E. sivalensis, and the deposits from which it came are probably 

 Upper Pliocene or early Pleistocene age. 



The dimensions of the tooth now described are : length 29, width 

 28, height of crown 38 mm. 



Hippopotamus Jiipponensis, Gaudry. (PI. XXI, Figs. 2-5.) 



Among the best preserved specimens are three teeth of a small 

 Hippopotamus, which, for reasons given below, may be referred 

 provisionally to the above-named species. The specimens are, 

 a lower premolar, probably p.m. 3 (PL XXI, Fig. 2), and two 

 upper posterior molars (Figs. 3-5), one of which is quite unworn. 



The species H. hipponensis was founded by Gaudry^ on teeth 

 occurring in Pliocene beds near Bone in Algeria. The premolar 

 is stated to be especially characterized by a very prominent postero- 

 internal cusp. The molars are not figured, but it is stated that they 

 do not present any important peculiarities. From this it would 

 appear that the sides of the columns were probably grooved so as to 

 give a trefoil pattern in wear, for the absence of such a marked 

 characteristic of most Hippopotamus molars could not well have 

 escaped Professor Gaudry's notice. For this reason it seems probable 

 that the teeth from the Pliocene of Casino, described and figured by 

 Pantanelli ^ as those of H. hipponensis, may in fact belong to another 

 and probably earlier species, since in them the trefoil pattern is 

 wanting, or, at least, obscure. The animal which Pomel * refers to 

 H. hipponensis, without giving any valid reasons for his determination, 

 seems to be quite different and is of Pleistocene age. 



For the present it will suffice to refer the specimens to Gaudry's 

 species, and defer more detailed consideration until further material 

 is available. 



1 Lydekker, "Siwalik and Narbada Equidaj": Mem. Geol. Surv. India, 

 Palseontologia Indica, ser. x, vol. ii, pt. 3 (1882), pi. xiii, fig. 1. 



2 Bull. Soc. Geol. France, ser. m, vol. iv (1876), p. 501, pi. xviii. 



3 Pantanelli, " Sugli strati Miocenici del Casino (Siena) " : Mem. E. Accad. 

 Lincei (3), vol. iii, p. 309, pi. iv, figs. 1-7 (1879). 



* Pomel, "Carte Geologique de I'Afrique — Paleontologie " : MonograpMe 

 No. 8, Les Hippopotames, p. 9 ; Algiers, 1896. 



