394 



SOLIPED1A. 



Fig. 154. 



appears, therefore, to have formed one of the links, now 

 lost, which connected the Horse with the Rhinoceros, and 

 it is interesting to observe that some of the extinct species 

 of Horse, in the analogous complexity of the enamel folds, 

 more closely resembled the Elasmothere than do the pre- 

 sent species. 



The canines are small in the Horse, 

 and rudimental in the Mare. I figure 

 here the fossil right lower canine of a 

 colt, found in the same cavernous fissure 

 (B) as the plicident molars, and proba- 

 bly, therefore, belonging to the same 

 species: the view of the inner side, given 

 in fig. 154, shows the folding in of the 

 anterior and posterior margins of the 

 crown, characteristic of the canines of 

 the genus Equus, and which is very 

 well marked in the present specimen. 

 The incisors associated with the plici- 

 dent molars offered no distinctive cha- 

 racters. 



Some of the bones of the extremities of the fossil Horse 

 from the same fissure (B) of the Oreston Caves, indicate an 

 animal about thirteen hands and a half high. The astra- 

 galus, reduced in fig. 155, one third the natural size, is a 

 very characteristic bone of the present genus ; the upper 

 articular surface, which is here represented, is oblique, and 

 the two convex ridges are divided by an unusually deep, 

 almost angular, valley ; the articular pulley, or trochlea, in 

 the lower end of the tibia has, of course, a corresponding form 

 the cavities and eminences being reversed ; by the depth 

 and obliquity of these, the tibia and astragalus of the Horse 

 may readily be distinguished from those bones in any other 



Lower canine tooth, 

 nat. size, Equus pticidens, 

 Oreston. 



