10 PROFESSOR OWEN ON THE CHARACTERS, ETC. 



Aristotle chose the locomotive system, and divided his Zootoka 

 — the equivalent of the Linnean Mammalia — into three sec- 

 tions : — 1st, DiPODA, or bipeds ; 2nd, Tetrapoda, or quadrupeds ; 

 and 3rd, Apod A, or impeds. The preponderating second group, 

 which includes all the class save the Human-kind and the Whale- 

 tribe, is subdivided into those with claws, and those with hoofs. 

 The unguiculate quadrupeds are again subdivided according to the 

 nature of their teeth ; the ungulate quadrupeds, according to the 

 divisions of their hoofs, as e. g. into Polyschidce, or multungulates, 

 DischidcB, or bisulcates, and Aschidce, or solidungulates. I need 

 scarcely remark that this, in most respects admirable, system, 

 would have commanded greater attention, and been now recognized 

 as more manifestly the basis of later systems, had its immortal au- 

 thor more technically expressed his appreciation of the law of the 

 subordination of characters ; but he applies to each of his groups, 

 whatever their value, the same denomination, viz. genos, or genus. 



Bay, with a less philosophical appreciation of the extent and 

 natui'e of the class Zootoka or Mammalia, arranges his equivalent 

 group of "Viviparous Four-footed Animals" chiefly on the Ari- 

 stotelian characters ; the primary division being into Ungtjlate 

 and XJnguicijlate, and the subdivisions being based on locomo- 

 tive and dental characters. 



Linnaeus, restoring the class Mammalia to its Aristotelian inte- 

 grity, primarily subdivides it into Ungfictjlata, Ungtjlata, and 

 MuTiCA, the latter being the ' Apoda' of Aristotle : the secondary 

 groups or orders are founded chiefly on modifications of the dental 

 system. 



Cuvier, adopting the same threefold primary division of the 

 class, subdivides it into better and more naturally defined orders, 

 according to various characters derived from the dental, the 

 osseous, generative, and the locomotive systems. 



lUiger, in primarily dividing the Mammalia into those with free, 

 and those with fettered limbs — the ' pedes exserti distincti,' con- 

 trasted with the ' pedes retracti obvoluti,' — made a more unequal 

 and less natural partition than the threefold one of Aristotle ; the 

 Seals and the Whales balance all the rest of the class in the 

 lUigerian system. The subdivisions, also, of these primary groups, 

 based exclusively on characters of locomotion, have met with little 

 acceptance beyond some of the schools of Grermany. 



De Blainville appears first, 1816, to have adopted a character 

 from the reproductive system for the primary division of the 

 Mammalia, viz. into the * Monodelphes,' * Didelphes,' and 'Ornitho- 



