GENERAL CHARACTERS 



5 



brigade, under the name of Diapsida, all the other orders, which 

 are characterised primarily by the possession of double or 

 separated temporal arches. 1 It has been pointed out, however, 

 that it is illogical to separate widely from one another groups like 

 the Chelonia, Sauropterygia, Rhynchocephalia, and Crocodilia, 

 all of which agree in the possession of abdominal ribs (modified 

 in the first into a true plastron); and, moreover, that the 

 Theromorpha differ much more widely from all other groups 

 of reptiles collectively than do any of the latter from one an- 

 other. 



An alternative classification, in which some of the groups ranked above as 

 orders are reduced to the grade of suborders, is the following: — 



Extinct Groups are marked with a t 



S be 



Em 





II. 



Order 



f Anomodontia 

 Anomodonts 



Rhynchocephalia 

 Tuateras 



Suborder 



1 



i Dicynodontia 



2 Theriodontia 



3 Cotylosauria 



4 Pariasauria 



i f Protorosauria 



Rhynchocephalia Vera 

 Acrosauria 



III. f Pelycosauria 

 IV. 



Squamata . 

 Snakes and Lizards 



V. Chelonia 



Tortoises and Turtles 



VI. Placodontia 

 Placodus 



VII. f Sauropterygia . 

 Plesiosaurs 



VIII. f Ichthyopterygia 

 Ichthyosaurs 



IX. Crocodilia . 

 Crocodiles 



X. fDlNOSAURIA . 



Dinosaurs 



XI. f Ornithosauria . 

 Pterodactyles 



i Lacertilia 

 I 2 Rhiptoglossa 



3 Ophidia 

 I 4 f Dolichosauria 



5 f Pythonomorpha 

 - i Cryptodira 

 I 2 Pleurodira 

 I 3 f Amphichelydia 

 *• 4 Trionychoidia 



, i Eusuchia 



•! 2 fAetosauria 



v 3 f Parasuchia 

 f i Theropoda 

 -! 2 Sauropoda 

 I 3 Ornithopoda 



The length of the foregoing lists, as compared with the one 

 dealing solely with existing forms, must very materially modify 



1 In the Squamata the lower temporal arch has disappeared. 



