4 SCOTT. [Vol. V. 



seems inclined to believe that the South American monkeys 

 have an entirely different origin from those of the Old World ; 

 or an even more striking example is the supposed dual origin 

 of the horse in the Old World and the New. 



Another aspect of this same question is the consideration of 

 the relative value to be given to resemblances and differences 

 in discussing the relationship between various groups. Huxley 

 (No. 13, p. 657) believes that, in forming natural orders, "it is 

 more important that similarities should not be neglected than 

 that differences should be overlooked." This, again, requires 

 the consideration of the nature of the resemblances and differ- 

 ences, whether they are due to advancing differentiation or to 

 the retention of primitive characters, whether the characters be 

 adaptive or inadaptive. Thus Flower says : " Too exclusive 

 attention has been paid to the characters of the teeth in defin- 

 ing the family divisions of the order. The difficulty in the 

 taxonomic use of these organs arises from the fact that the 

 teeth of all the members of such a limited and well-defined 

 group as the terrestrial or fissipedal Carnivora are formed on 

 the same general type, but with infinite modifications of this 

 type. And as these modifications are mainly adaptive, and not 

 essentially indicative of affinity, they reappear in various 

 degrees and combinations in many of the great natural divis- 

 ions of the order" (No. 10, p. 5). Wallace, on the other hand, 

 insists upon the instability of inadaptive characters (No. 34, 

 p. 138). The classification of the Carnivora by the characters 

 afforded by the base of the skull, as proposed by Turner and 

 Flower, is rejected by Schlosser (No. 28, p. 236) on the ground 

 of his studies of extinct forms. " Aus all dem gesagten geht 

 so viel hervor, dass die als Aeluroidea zusammengefassten 

 Formen in einigen Punkten einen gemeinsamen Entwicklungs- 

 process verfolgen. Das berechtigt aber noch lange nicht, auf 

 eine nahere Verwandtschaft zu schliessen." In the same way 

 the relations of the various forms of marsupials to the placental 

 orders form the subject of endless diversities of opinion. The 

 question as to the relative taxonomic value of the feet and the 

 teeth has been very hotly disputed, and the list might be 

 indefinitely extended, showing how the construction of phylo- 

 genies depends upon the answer to this problem of convergence 

 in its protean forms. 



