1388 THE MALAYAN PAPILIONIDE 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 Galeopithecus, 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 
