138 THE MALAYAN PAPILIONID& AS 



whole structure, in which no organ or function has 

 attained an undue prominence. 



Turning now to the Mammalia, it might be argued 

 that as they are pre-eminently the terrestrial type 

 of vertebrates, to walk and run well is essential to the 

 typical perfection of the group ; but this would give 

 the superiority to the horse, the deer, or the hunting 

 leopard, instead of to the Quadrumana. We seem here 

 to have quite a case in point, for one group of Quad- 

 rumana, the Lemurs, is undoubtedly nearer to the 

 low Insectivora and Marsupials than the Carnivora or 

 the Ungulata, as shown among other characters by 

 the Opossums possessing a hand with perfect opposable 

 thumb, closely resembling that of some of the Lemurs ; 

 and by the curious Graleopithecus, which is sometimes 

 classed as a Lemur, and sometimes with the Insecti- 

 vora. Again, the implacental mammals, including 

 the Ornithodelphia and the Marsupials, are admitted 

 to be lower than the placental series. But one of the 

 distinguishing characters of the Marsupials is that the 

 young are born blind and exceedingly imperfect, and 

 it might therefore be argued that those orders in 

 which the young are born most perfect are the highest, 

 because farthest from the low Marsupial type. This 

 would make the Ruminants and Ungulata higher than 

 the Quadrumana or the Carnivora. But the Mam- 

 malia offer a still more remarkable illustration of the 

 fallacy of this mode of reasoning, for if there is one 

 character more than another which is essential and 

 distinctive of the class, it is that from which it derives 



