34 EXTINCT EDENTATES. [CH. I 



reproductive organs. On the other hand, the Oryctero- 

 podidse are not so nearly allied to Manis as are the 

 different genera of New World Edentates among them- 

 selves. But though this is the case it does not show 

 any special affinities with the New World forms. It may 

 be temporarily regarded as a distinct family having 

 (at present) problematic relations to the Manidse, which it 

 resembles by what are principally negative characters. 

 The placenta is an organ which is of great assistance 

 in bringing out affinities between various groups of 

 mammals; unfortunately it is not known whether the 

 placenta of Orycteropus is deciduate or the reverse ; if 

 non-deciduate there is a likeness to the Manis and not to 

 the New World Edentates. At any rate it is clear that 

 Manis, even if it be not a close ally of Orycteropus, is still 

 further removed from the Myrmecophagidae, Dasypodidse 

 or Bradypodidse. A glance at the structure of the fossil 

 members of the order entirely confirms the broad lines 

 of classification thus laid down by Sir William Flower. 

 The Megatheriidse are in some respects intermediate 

 between the anteaters and the sloths; the teeth are those 

 of the sloths, but the diminution of their number in 

 the genus Goelodon " leads towards their total suppression 

 in Myrmecophaga." The lengthening of the skull in 

 Megatherium is another step in the direction of Myrme- 

 cophaga. On the other hand the Old World Edentates of 

 the tertiary period, so far as they are known, lend support 

 to the view that they are more nearly related to the 

 existing Edentates of that part of the world. We have 

 therefore in this group the closest relation between the 



