or THE CLASS MAMMALIA. 26 



Ltencephala. Lissencephala. 



Didelphys and Fhascogale . . Soricidce. 



JDasyuridcB Centetes, Gymnv/ra. 



Echidna Manis. 



OrnithorhyncJius Orycteropus. 



The classification proposed by M. Gervais, already cited (p. 16), 

 in which the Bodentia, Cheiroptera, and Insectivora are associated 

 in the same high primary group with the Quadrumana and Bimana, 

 is avowedly adopted from that previously proposed by Prof. Milne- 

 Edwards*. 



In next proceeding to consider the subdivisions of the Gyren- 

 cephala, we seem at first to descend in the scale in meeting with a 

 group of animals in that subclass, having the form of Fishes ; but a 

 high grade of mammalian organization is masked beneath this 

 form. The Gyrencephala are primarily subdivided, according to 

 modifications of the locomotive organs, into three series, for which 

 the Linnean terms may well be retained ; viz. Mutilafa, TTngulata 

 and TInguiculata, the maimed, the hoofed, and the clawed series. 



These characters can only be applied to the Gyrencephalous 

 subclass ; i. e. they do not indicate natural groups, save in that 

 section of the Mammalia. To associate the Lyencephala and 

 Lissencephala with the unguiculate Gyrencephala into one great 

 primary group, as in the Mammalian systems of Eay, Linnaeus 

 and Cuvier, is a misapplication of a solitary character akin to that 

 which would have founded a primary division on the discoid pla- 

 centa or the diphyodont dentition. No one has proposed to asso- 

 ciate the unguiculate Bird or Lizard with the unguiculate Ape ; 

 and it is but a little less violation of natural affinities to associate 

 the Monotremes with the Quadrumanes in the same primary 

 (unguiculate) division of the Mammalian class. 



The three primary divisions of the Gyrencephala are of higher 

 value than the ordinal divisions of the Lissencephala ; just as 

 those orders are of higher value than the representative families 

 of the Marsupials. 



The Mutilata, or the maimed Mammals with folded brains, are 

 so called because their hind-limbs seem, as it were, to have been 

 amputated; they possess only the pectoral pair of limbs, and 

 these in the form of fins : the hind end of the trunk expands into 

 a broad, horizontally flattened, caudal fin. They have large brains 

 with many and deep convolutions, are naked, and have neither 

 neck, scrotum, nor external ears. 



* See note at p. 16. 



