VII CHARACTERS — CLASSIFICATION 279 



aud ultimately Splienodon was recognised as deserving a separate 

 position, equal in rank to the other groups. Stannius showed 

 that the Crocodiles and Tortoises are relatively near allies in 

 opposition to the likewise closely allied Lizards and Snakes 

 (Sphenodon was then unknown), and he expressed this by the 

 term Monimostylica, or creatures with fixed quadrate bones, for 

 the former, and Streptostylica, creatures with movable quadrates, 

 for the latter combination. The fossil Eeptiles were hardly 

 allowed proper places in the system. In various zoological text- 

 books they were, or are even now, treated as inconvenient, out- 

 lying, or supernumerary members. A long time elapsed before, 

 thanks to the labours of H. von Meyer, Owen, Huxley, Marsh, 

 Cope, Zittel, and Seeley, it was recognised that the extinct groups 

 form the preponderant mass of Eeptiles, and that it is the recent 

 groups which, in spite of the bewildering number of species of 

 Lizards and Snakes, are the comparatively few and much-reduced 

 members of a once flourishing class. With the exception of the 

 Lizards and Snakes, which are on the ascending branch, the 

 modern Splienodon, the Crocodiles and the Tortoises are a mere 

 fraction, comprising a few survivals of richly-developed groups, 

 while all the others, the overwhelming majority, have died out. 

 The classification adopted in this volume is as follows : — 



Class Eeptilia. 



Sub-Class I. Proreptilia. 

 „ II. Prosauria. 



Orders : Microsauri, Prosauri. 

 III. Theromorpha. Orders : . Pareiasauri, Tlieriodontia, 

 Anomodontia, Placodontia. 

 'N IV. Chelonia. Orders : Atlieoae, Thecophora. 



V. Dinosauria. Orders : Sauropoda, Theropoda, Ortliopoda, 

 V Ceratopsia. 



^VI. Crocodilia. Orders : Pseudosucliia, Parasuchia, Eusuohia. 

 \, VII. Plesiosauria. Orders : Notliosauri, Plesiosauri. 



„ VIII. Ichthyosauria. 



„ IX. Pterosauria. 



X. Pytlionomorplia. Orders : Dolichosauri, Mosasauri. 

 "~^ XI. Sanria. Orders ; Lacertilia, Opliidia. 



The eleven principal groups are here called " sub-classes " to 

 emphasise the undeniable fact that these Eeptilian groups are of 

 much greater morphological value than those which are most 

 generally called " Orders " in the Mammaha, that class which we 

 consider as the standard or model of classificatory units. The 



