480 ON THE TRIASSIC REPTILE TELERPETON ELGINENSE. [Apr. 1 9, 



the Mammalia through the Anomodontia, the Cotylosauria being 

 a side-branch issued fi'om the Pai-iosauria. The Rhynchocephalia 

 may have been evolved out of the Microsauria, and branched off 

 into many phyla, one of which culminated in the Birds. My 

 objection to the Chelonia and Plesiosaui-ia being placed with the 

 Pariosauria or Anomodontia rests on the ground that it cannot 

 be conceived that these two orders could have been derived from 

 forms in which the quadrate is more or less reduced, the plastron, 

 or system of " abdominal ribs," has disappeared or at any rate 

 become extremely reduced, and in which the pelvis slants back- 

 wards, all features which are the opposite of those chai-acteristic 

 of the Ohelonia and Plesiosauria. 



The following diagram expresses what I regard as the probable 

 phylogenetie relations of the orders of Reptiles with which we are 

 at present acqviainted : — 



MAMMALIA. 



AVES. 





< 



P5 



III. Anomodontia. 



II. Cotylos.iuria. 



I. Pariosauria. 



\ 

 \ 



j Labyrinthodontia. 



XV. Ornithosauria. 



XVI. Squamata. 



XII. Enij'doRauria. 



VI. Acrosauria. 



V. Pelj'cosauria 



XIV. Orthopoda. 



XIII. Dinosauiia. 



XI. Ichtliyosauria. 



X. Plesiosauria. 



VIII. Chelonia. 



IV. Rhyncliocephalia 



Microsauria. 



BATRACHIA STEGOCEPHALA. 



For obvious reasons, I cannot accept the names Synapsida and 

 Diapsida for the two phylogenetie series. I will designate the 

 first subclass by the name Theromora of Cope, in a restricted 

 sense, and suggest for the second that of Herpetomorpha. The 

 Theromora may be divided into three orders, the Herpetomorpha 

 into thirteen. 



