le ee ee 
ee ee ree ee et er mee 
Prof. Owen on the Class Mammalia. 15 
I have been induced to dwell thus long on the dental charac- 
ters of the class Mummalia, because they have not been clearly 
or accurately defined in any systematic or elementary work on 
zoology, although an accurate formula and notation of the teeth 
are of more use an see in characterizing genega -in this than 
in any other class of anim 
I next proceed to review brie efly the a om primary divi- 
sions of the Adammalia hitherto proposed. est authorities 
in Natural History have adopted different Phelan, drawn from 
different systems of organs, for the primary groups or dhivikious 
of the class Mammalia. 
Aristotle chose the locomotive system, and divided his Zo- 
the Wha pe is su ad velba into those weit claws, and those 
with aie The unguiculate quadrupeds are again subdivided 
according to the nature of their teeth; the ungulate quadrupeds, 
according to the divisions of their hoof, as e. g. into Poly yschidee, 
or multungulates, Dischide, or bisuleates, and Aschide, or solid- 
ungulates. I nee scarcely remar that. this, in most r respects 
admirable system, docks have commanded greater attention, 
een now recognized as more manifestly the basis of later 
systems, had its immortal author more technically expressed his 
appreciation of the law of the subordination of characters; but 
he applies to each of _ groups siamaees their value, the same 
denomination, viz. 0 
Ray, with a less shied pees 6, of the extent and 
nature of the class Zootoka or Mammalia, arranges his eee 
group of “ Viviparous Four-footed animals” chiefly on the Aris- 
totelian characters; the primary division being et Un a LATE 
and Unavicunare, and the subdivisions being based on locomo- 
tive and dental characters 
Linnzeus, restoring the ‘class Mammalia to its Aristotelian in- 
tegrity, primarily subdivides it into Unevicutara, UNGULATA, 
“ Mvur the latter being the ‘Apoda’ of Aristotle : the 
aaiiay. groups or orders are founded chiefly on modifications 
of the dental system. 
uvier, adopting the same threefold primary division of the 
class, subdivides it into better and more naturally defined orders, 
according to various characters derived = the dental, the 
osseous, generative, and the locomotive system 
lliger, in primarily dividing the Mawnan into those with 
free, and those with fettered limbs—the ‘pedes exserti distincti,’ 
contrasted with the ‘pedes retracti obvoluti,—made a more 
unequal and less natural partition than the threefold one of Aris- 
