SIWALIK AND NARBADA EQUIDiE. 
13—79 
Limb-bones. — In plates LXXXIY and LXXXV of the “ Eauna Antiqua 
Sivalensis ” a large series of limb-bones of Siwalik equine animals has been 
lithographed, and in many cases specifically assigned either to Equus sivalensis 
or Hippotherium antilopinum . We are not, however, informed on what grounds 
these determinations were made, but it appears that in general the larger speci- 
mens have been assigned to the former species, and the smaller to the latter. 
If, however, we examine into the matter more closely, we shall find that this does 
not hold as an invariable rule. Taking the case of the metatarsus, we find that 
in figure 4 of plate LXXXIY a specimen of this bone referred to Equus siva- 
lensis has a length of 1L1 inches ; while a specimen (plate LXXXY, figure 12) 
referred to Mippotherium antilopinum has a length of 10'4 inches. Another 
specimen, however (plate LXXXIY, figure 21), assigned to the former genus, 
has a length of only 10 ‘5 inches, and is much slenderer than the first specimen. 
In the Indian Museum there is a specimen of an equine metatarsus from the 
topmost Siwaliks, in which hitherto no remains of Rippotherium have been found : 
this bone is somewhat smaller than the one assigned by Ealconer and Cautley to 
H. antilopinum , and yet belongs to an Equus. It will be shown below that the 
proximal phalangeal bones referred by Ealconer and Cautley to EL. antilopinum 
really belong to Equus sivalensis. 
Erom the foregoing considerations it seems to me that Ealconer’s identification of 
the limb-bones of this species is certainly erroneous, and, therefore, that M. Gaudry ’s 
conclusions as to the probable monodactyle character of H. antilopinum , based on 
the absence of the facettes for the lateral metacarpals or tarsals, on the ‘ cannon- 
bones ’ assigned to this species by Dr. Ealconer, must likewise fall to the ground. It 
may be observed, however, that if, as was almost certainly the case, the hippotheres 
have been gradually modified into the true horses, they must at some time or other 
have lost their accessory digits, and the anterior ‘ pillar ’ of the upper molars must 
have been become connected with the main body of the tooth. It is quite possible, 
therefore, if not probable, that these changes did not take place synchronously, 
and, accordingly, there would be nothing improbable in meeting with an animal 
having, as M. Gaudry considers to have been the case with the present species, the 
digitation of the horse, coupled with the dentition of the hippothere. 
There are but few limb-bones in the Indian Museum, which can with any cer- 
tainty be referred to this species. Among these may be mentioned the proximal 
phalangeals, which are of the same shape as the corresponding bone of the next 
species (plate XIII), but about two-thirds the size. They are quite different from 
the bone assigned by Ealconer to this species in the “ Eauna Antiqua Sivalensis, ” 
plate LXXXIY, figure 11. 
Comparison with E. gracile. — As far as can be judged, it appears probable 
that Dr. Ealconer distinguished his Indian hippothere from the European species 
on the ground of its smaller size. M. Gaudry, however, in his . great works on 
the Pikermi and Mount Leberon fossils, has shown that the latter species is subject 
