574 UNGULATA. 



Hyiacoidea. This is as it should be, for there are no specially 

 Ungulate features about either of the two latter, and when care- 

 fully surveying the facts, it is difficult to understand upon what 

 grounds they have been and are classed with the hoofed animals. 

 But the definition if strictly appHed goes further than this and 

 excludes from the Ungulates a certain number of extinct forms, 

 which ought perhaps to be placed with them. Such are the 

 Lipoterna (e.g. Macrauchenia) which appear to have all the 

 Ungulate characters mentioned except the interlocking carpals 

 and tarsals and the universal absence of digit No. 5 on the pes. 

 It is true that this group has some remarkable characters of its 

 own, but in the present state of knowledge it may fairly be left 

 with the Ungulata. A case might also be made out for including 

 the Toxodontia and the Amblypoda, but after careful considera- 

 tion they must, we think, be excluded. It is true that both these 

 groups present some of the ungulate features, but they are 

 without the others, and they both present remarkable features 

 of their own, which, we feel convinced, would exclude them from 

 the group were they alive at the present day so that we could 

 study their soft parts. We refer especially to the structure of 

 the brain as revealed by casts of their skulls. 



There remain the Typotheria, Ancylopoda and the Condy- 

 lartha. These are dealt with fully below. Here it is only 

 necessary to say that the two latter, though showing some 

 ungulate features depart far too widely from that type to be 

 included with it in classification ; and that the Typotheria differ 

 from the Ungulata in all their characters. 



In maintaining these opinions as to the limitations of the order 

 Ungulata, we are in opposition to the views of many eminent 

 zoologists, men who have devoted much thought, labour and 

 research to the study of these obscure remains. We therefore 

 urge our views with much diffidence and have only decided to 

 give expression to them after considerable hesitation. But we 

 feel that we cannot evade the matter in a treatise of this kind. 

 We are obliged to look into the facts and in forming a judgment 

 upon them we must exclude from our minds as far as is possible 

 all that bias which comes so readily from theoretical predilec- 

 tions. 



Dentition.* The back teeth are nearly always rooted and may 



* See pp. 499-508. 



