based on the Principle of Cephalization. 



263 



theiiic, a microsthenic, and a degradational ; the first to include 

 the genera Phalangista, Dasyurus, Macropus, Diprotodon, &c.; 

 the second, Perameles, Didelphys, Phascolorays, Echidna, &c., or 

 Marsupial Insectivores, Rodents, and Edentates ; the third^ Or- 

 nithorhynchus. 



The following table presents to view the subdivisions of Mam- 

 mals and its orders. Under Obtocoids, the relations of the two 

 higher groups are indicated by the above adjectives, without giv- 

 ing them special names : — 



Mammals, 

 a. Man. 

 /8. Megasthenes. 

 y. Microsthenes. 

 D. Ootocoids, 



Megasthenes. 

 Quadrumanes. 

 Carnivores. 

 Herbivores. 

 Mutilates. 



Microsthenes. 

 Chiropters. 

 Insectivores. 

 Kodents. 

 Edentates. 



Ootocoids. 



Megasthenic. 

 Microsthenic. 

 Ornithorhynchs. 



4. Higher subdivisions of the classes of Birds, Reptiles, and 

 Fishes. — (1.) In the class of Birds, there are three grand divi- 

 sions : the first two, as recognised by Bonaparte, are the Altrices 

 (Rapacious birds, Perchers, &c., and other birds that feed their 

 young until they can fly), and the Prcecoces (or the Gallinse, An- 

 seres, Ostriches, &c., which feed themselves as soon as hatched). 

 The third includes the Reptilian Birds or Erpetoids (p. 77). 

 The terms Pterosthenics and Podosthenics apply equally well 

 with Altrices and PrcGcoces to the two higher divisions of Birds, 

 as explained on page 83, and have an advantage in their direct 

 dynamical signification. 



The type of ordinary Birds (or Pterosthenics and Podosthenics) 

 is stated on page 95 to be essentially limitate, like that of In- 

 sects, while the type of Erpetoids is multiplicate, like that of 

 Myriapods or of ordinary Reptiles ; so that the relation of 

 Erpetoids to the higher division of Birds is in an important re- 

 spect analogous to that of Myriapods to the higher division of 

 Insecteans. 



(2.) In the classification of Reptiles there are three prominent 

 types of structure recognised by Erpetologists ; (1 .) That of the Che- 

 lonians ; (2.) That of the Lacertoids (including Saurians, Lizards, 

 Snakes) ; and (3.) The degradational or hemitypic one of Am- 

 phibians. It is now well known that Snakes and Lizards are 

 alike in type of structure, the two groups graduating almost in- 

 sensibly into one another, some species ranked as Lizards being 

 footless like the Snakes. The Snakes constitute the degrada- 

 tional group under the Lacertoids. The Amphibians, constitut- 

 ing the third order, are on the same level with the Erpetoid 

 Birds and the Ootocoid Mammals, as presented in the following 

 table. 



