466 Reviews — Prof. Edward J). Cope — 



We now turn to the group division of hoofed mammals. The first 

 order, which the author names Taxeopoda, comprises animals, in 

 which the carpus and tarsus form two rows, with the bones of the 

 first row supported by the second row, each for each, so as not to 

 alternate. The order is defined as having the scaphoid bone supported 

 by the trapezoid, and the lunar bone supported by the magnum. The 

 cuboid bone articulates proximally only with the calcaneum. This 

 group comprises the Hyracoidea, in which the fibula articulates with 

 the astragalus, and the ungual phalanges are truncate ; secondly, 

 the Condylarthra, in which the fibula does not articulate with 

 the astragalus or calcaneum, and the ungual phalanges are pointed. 

 A third group may be formed by the Toxodontia, or the Toxodontia 

 may belong to the Proboscidea. 



The Amblypoda is an order which is subdivided into two groups, 

 first, Pantodonta, which has a third trochanter to the femur, and 

 incisor teeth in the upper jaw ; and secondly, Binocerata, which 

 has no upper incisors, and no third trochanter. The Amblypoda 

 are defined from the Proboscidea, chiefly by the shortness of the 

 navicular bone, which allows the cuboid bone to articulate with the 

 astragalus. 



The name Diplarthra is used as an ordinal name for the Perisso- 

 dactyla and Artiodactyla, in place of the name Ungulata, which is 

 made to include all hoofed mammals. 



This classification is exhibited in the following diagram : — 

 Taxeopoda. 



Condylarthra Platyarthra 



i I (hypothetical). 



Hyracoidea | j 



Proboscidea Amblypoda 



I 

 Taligrada 



Hyodonta Pantodonta 

 (hypothetical) . | 



| Dinocerata 

 Diplarthra 



I I 



Perissodactyla. Artiodactyla. 



The carpal modification which characterizes the Diplarthra is 

 explained as a rotation of the bones of the second carpal row upon 

 those of the first row, in which they move to the inner side, a con- 

 dition attributable to the loss of the pollex, by which the weight of 

 the body is thrown chiefly on the third and fourth digits. And 

 seeing that this condition has brought about the alternation of the 

 two rows of carpal bones, producing a stronger carpus, the author is 

 disposed to regard the modification as accounting tor the survival of 

 the Diplarthra, while most of the mammals which have a serial 

 arrangement of the carpal bones have become extinct. 



The Amblypoda is intermediate between the Taxeopoda and Di- 

 plarthra, in having the carpus of the more complicated type. The 

 Taxeopoda approach most nearly to the Bunotheria, especially the 

 Mesodonta, from which they are distinguished by their hoofs, 



