34 PKOEESSOB OWEN ON THE CHAEAGTEBS, ETC. 



flexile movements, and terminated by a hand of matchless per- 

 fection of structure, the fit instrument for executing the behests 

 of a rational intelligence and a free will. Hereby, though naked, 

 Man can clothe himself, and rival all native vestments in warmth 

 and beauty ; though defenceless, Man can arm himself with every 

 variety of weapon, and become the most terribly destructive of 

 animals. Thus he fulfils his destiny as the supreme master of 

 this earth, and of the lower Creation. 



In these endeavours to comprehend how Nature has associated 

 together her mammalian forms, the weary student quits his task 

 with a conviction that, after all, he has been rewarded with but 

 an imperfect view of such natural association. The mammalian 

 class has existed, probably from the triassic, certainly from the 

 lower oolitic period; and has changed its generic and specific 

 forms more than once in the long lapse of ages, during which life- 

 work has been transacted on this planet by animals of that high 

 grade of organization. Not any of the mammalian genera of the 

 secondary periods occur in the tertiary ones. No genus found in 

 the older eocenes (plastic and septarial clays, &c.) has been dis- 

 covered in the newer eocenes. Extremely few eocene genera occur 

 in mioeene strata, and none in the pliocene. Many miocene ge- 

 nera of Mammalia are peculiar to that division of the tertiary 

 series. Species indistinguishable from existing ones begin to ap- 

 pear only in the newer pliocene beds. Whilst some groups, as 

 e. g. the Perissodactyles and omnivorous Artiodactyles, have been 

 gra'dually dying out, other groups, as e. g. the true B/uminants, 

 have been augmenting in genera and species. 



In many existing genera of different orders there is a more 

 specialized structure, a greater deviation from the general type, 

 than in the answering genera of the miocene and eocene periods ; 

 such later and less typical Mammalia do more effective work by 

 their more adaptively modified structures. The E-uminants, e. g. 

 more effectually digest and assimilate grass, and form out of it a 

 more nutritive and sapid kind of meat, than did the antecedent 

 more typical or less specialized non-ruminant Herbivora. 



The monodactyle Horse is a better and swifter beast of draught 

 and burthen than its tridactyle predecessor the miocene Hippa' 

 Hon could have been. The nearer to a Tapir or a Rhinoceros in 

 structure, the further will an equine animal be left from the goal 

 in contending with a modern Eacer. The genera Felis and Ma- 

 chairodus, with their curtailed and otherwise modified dentition and 



