MAMMALIA, 523 



liocene and Upper Miocene ; Anchitherium^ an animal about the size 

 a sheep, with three functional toes (like the rhinoceros), is found in 

 le late Miocene ; whilst a similar form in the early Miocene shows the 

 ;;stige of the fifth toe as a small mef.apodial splint-bone. Pachynolophus 

 the Upper Eocene and Hyracotheriuni of the Lower Eocene were 

 1 smaller (about the size of a hare), and in the front-limb they had 

 )ur toes (2, 3, 4 and 5) and three on the hind — in fact, resembling in 

 lis feature the tapirs ; one species of rachynolophus shows a vestige 

 f the first digit in the presence of a splint-like metacarpal. These 

 ^pes also show the changes in other structural features, such as the 

 :eth. (See Fig. 361.) 



In the New World the same series has been made out and carried 

 ack even further to the little Phenacodus of the Eocene, with five per- 

 ict plantigrade digits and a complete dentition, which, with its allies, 

 )rms a meeting point of the modern Ungulata. 



A very interesting' point is the separate series of the New and Old 

 Vorld, and it has been maintained with much reason that the horse 

 vas independently evolved in the two hemispheres. 



In the case of the ox a similar series can be made out, true Bovidi^ 

 lating back to the Upper Miocene, whilst forms allied to the pigs and 

 hevrotains go back to the Eocene. On this point we may quote 

 ^ower and Lyddeker : — "The primitive Artiodactyles, with the typical 

 lumber (44) of incisor, canine and molar teeth, brachydont molars, 

 :onical odontoid process, four distinct toes on each foot, with meta- 

 3odial and all carpal bones distinct, no frontal appendages, and (in all 

 Drobability) simple stomach and diffused placenta, were separated at a 

 very early period into Bunodonts and Selenodonts, although there is 

 evidence of intermediate forms showing a complete transition from the 

 one modification to the other. These and other fossil forms so com- 

 pletely connect the four groups — Suina, Tylopoda, Tragulina and 

 Pecora — into which the existing members of the sub-order have become 

 divided, that in a general classification embracing both living and ex- 

 tinct forms these divisions cannot be maintained." 



4 and 5. — The Dog {Canis familiaris) and Cat (^Felis 

 domesticus), — Transition Cursorial Types. 



The dog and cat are examples of mammals which, whilst 

 having fully adopted the quadrupedal terrestrial mode of 

 life, have retained the varied use of their limbs in other 

 directions to such an extent that these limbs do not show 

 complete adaptation to a cursorial habit. 



Both belong to the large and important order of Carni- 

 vora, which, in the most typical representatives, feed upon 

 the flesh of other mammals. This is usually the case with 

 both the dog and cat, but the latter, like the whole 

 family of Felidce^ is in this respect the most typical of all 



