CH. I] STRUCTURE OF EDENTATES. 33 



uniting of the Old World with the New World anteaters. 

 But an examination of other structures does not show 

 any likeness between the Manis and the Myrmecophaga, 

 but does reveal an unmistakeable resemblance between 

 the latter and the sloth, to which it is so unlike in 

 external form and in habits. In the American anteater 

 the vertebrae to a large extent interlock with each other 

 by an additional series of articular processes, not found 

 in other mammals, excepting only the Dasypodidse, and 

 the extinct Megatheriidse, and which is to a less extent 

 but still obvious in the sloths. This structural resem- 

 blance found in animals of such diverse habit must have a 

 significance in considering their affinities. The fact that 

 the processes in question are in a rudimentary condition 

 in the sloths is correlated with the fact that in those 

 animals which depend from the branches of trees, and use 

 the muscles of the back but little, the articular processes 

 generally of the spine are poorly developed; the fact is 

 they are of even greater importance as evidence of real 

 blood relationship. As Sir William Flower says, the fact 

 may be almost said to prove " that the sloths are 

 descended from animals in which they existed in a fully 

 developed form." Neither in Manis nor in Orycteropus 

 are there the slightest vestiges of these additional articu- 

 lar processes. It is also pointed out that the shape of the 

 sternum is characteristic of the New World and the Old 

 World Edentates respectively. When we come to other 

 details of structure there is the same alliance to be noted 

 between the various families of Edentata found in America, 

 more particularly is this to be seen in the anatomy of the 

 B. z. 3 



