666 



MAMMALIA 



[CH. 



and we may take as a further mark of degeneracy the almost com- 

 plete disappearance of the milk set of teeth. The penis has the 

 same structure as in Metatheria. 



Order I. Edentata. 



When we take a general survey of the orders or main divisions 

 into which the Eutheria are divided we find that we have three or 

 four strange groups, the relations of which to the others are most 

 difficult to decide. These include the curious Edentata of South 

 America, comprising three families, the BRADYPODIDAE or Sloths, the 

 MYRMECOPHAGIDAE or American Ant-eaters, and the DASYPODIDAE 

 or Armadillos. With these the South African forms, included in 

 the families MANIDAE or Scaly Ant-eaters and ORYCTEROPODIDAE 



- mm 



Fia. 333. Tamandua Ant-eater, Tamandua tetradactyla. From Proc. Zool. 



Soc. 1871. 



or Cape Ant-eaters, are usually grouped, though their relationship 

 is a matter of doubt, and it seems clear that they have no close 

 relationship to the South American forms, for which reason we shall 

 use for these African families the name Effodientia. The name 

 Edentata means " toothless," and was given to the animals of this 

 group by the early naturalists because they supposed them to 

 be devoid of teeth. This is only the case with one small family, 

 the Ant-eaters, or MYRMECOPHAGIDAE, which like Echidna, have 

 lost their teeth through disuse. In the rest there are teeth, 

 but front teeth are always wanting. In the adult none of the 

 teeth have enamel and all are similar to each other. The 

 hands and feet are armed with great curved claws, adapted 

 for holding on to supports, not for grasping or attacking, and 



