EDWARD D. COPE. 



69 



period which elapsed since the Permian epoch inclusive, 

 for it is then that the Reptilia enter the held of our 

 knowledge. During this period but one order of repti les 

 inhabited the earth, so far as now known, that of the 

 Theromorpha. The important character and role of this 

 type may be inferred from the fact that they are struc- 

 turally nearer to both the Batrachia and the Mammalia 

 than any other, but present characters which render it 

 probable that all the other reptiles, with possibly the ex- 

 ception of the Ichthyopterygia, derived their being from 

 them. The phylogeny may be thus expressed : 



Dinosauria Testudinata 

 (Crocodilia) 



Pterosauria 



Rhynchocephalia Lacertilia Ophidia 



Pythonomorpha 



Sauropterygia 



Ichthyopterygia 



Theromorpha 



In the first place, this line departs with lapse of time 

 from the primitive and ancestral order, the Theromorpha, 

 in two respects. First in the loss of the capitular artic- 

 ulation 6f the ribs, and second in the gradual elonga- 

 tion and final freedom of the suspensory bone of the 

 lower jaw (the os quadratum). In so departing from the 

 Theromorpha, it also departs from the mammalian type. 

 The ribs assume the less perfect kind of attachment 

 which the mammals only exhibit in some of the whales, 

 and the articulation of the lower jaw loses in strength, 

 while it gains in extensibility, as is seen in the develop- 

 ment of the line of the eels among fishes. The end of 

 this series, the snakes, must therefore be said to be the 

 result of a process of creation by degeneration, and their 

 lack of scapular arch and fore limb and usual lack of 



53 



