242 THE MAMMALIA. 



than what was known to Cuvier. Although the two 

 groups, in their outward appearance and mode of 

 life, show affinity to the Eodents with claw-like 

 hoofs, their molar teeth are singularly like those of 

 most of the Ehinoceros tribe. There is absolutely 

 no safe starting point for their historical descent. 1 

 We are more fortunate as regards the class next 

 to be considered, the Sirenia. 



6. THE SIKENIA, OR SEA-COWS. 2 



Of this group the dugong (Halicore dugong) 

 lives in the Eed Sea, the Manatus frequents the 

 West Coast of Africa, and another species the 



1 Cope is inclined to think that the arrangement of the 

 carpals in the Hyrax is a sign of very ancient descent. His 

 main reason for this supposition is the fact that the bones form- 

 ing the several rays of the fingers still lie one behind the other 

 simply and regularly, as in the case of the lower vertebrates ; 

 whereas in other mammals not, however, in the elephant the 

 two rows of carpals have been displaced and lie side by side. 

 The cause of this displacing or twisting must, without doubt, be 

 looked for in the loss of the thumb, which again is connected 

 with the cases of adaptive and inadaptive transformations of the 

 carpals mentioned by Kowalewsky. As, however, in the elephants 

 the row of carpals is not displaced, while in the Coryphodons a 

 very marked displacement has taken place in spite of the thumb 

 having been retained, it seems to me that Cope's attempt to 

 arrange and determine the general relationships of the Hoofed 

 Animals, more particularly of the earliest Eocene fauna, from 

 these circumstances, is much too unsafe. 



2 Lepsius, Halitherium Scliinzii. Darmstadt, 1881. 



