350 PALEONTOLOGY AND EVOLUTION XI 



second premolar has an anterior prolongation ; and 

 that the posterior molar of the lower jaw has, as 

 Cuvier pointed out, a posterior lobe of much 

 smaller size and different form, the dentition of 

 Ancliithcrium departs from the type of the 

 Pakeothcriwn, and approaches that of the Horse. 



Again, the skeleton of Ancliithcrium is ex 

 tremely equine. M. Christol goes so far as to 

 say that the description of the bones of the horse, 

 or the ass, current in veterinary works, would fit 

 those of Anchithcrium. And, in a general way, 

 this may be true enough ; but there are some most 

 important differences, which, indeed, are justly 

 indicated by the same careful observer. Thus the 

 ulna is complete throughout, and its shaft is not a 

 mere rudiment, fused into one bone with the 

 radius. There are three toes, one large in the 

 middle and one small on each side. The femur is 

 quite like that of a horse, and has the character 

 istic fossa above the external condyle. In the 

 British Museum there is a most instructive 

 specimen of the leg-bones, showing that the fibula 

 was represented by the external malleolus and by 

 a flat tongue of bone, which extends up from it 

 on the outer side of the tibia, and is closely 

 ankylosed with the latter bone. 1 The hind toes 



1 I am indebted to M. Gervais for a specimen which indicates 

 that the fibula was complete, at any rate, in some cases ; and 

 for a very interesting ramus of a mandible, which shows that, 

 as in the Palccotlicria, the hinderniost milk-molar of thu lower 



