EDWARD COPE 85 



and of puny strength a fruitful law of which the 

 exact formula seems indeed to be due to Cope, and 

 which serves as a real clue to the researches of 

 modern palseontology. 



After having thus attempted to unravel or to 

 render precise some of the great laws of the evolu- 

 tion of beings, Cope applies his theoretical ideas 

 to the phylogeny of the Vertebrates. The great 

 palaeontological discoveries in America enable the 

 lines of precise descent of several small groups 

 to be determined, and even give us a glimpse 

 of the phylogenetic relations of some of the orders 

 or classes of this great division of the animal kingdom. 

 In accordance with his theoretical ideas, Cope strives 

 to show that the evolution of the Vertebrates has 

 been not only progressive, but more often than it was 

 supposed, regressive ; this last feature being more 

 frequent in the lower than in the higher groups. 



Leaving on one side the two lower groups of the 

 Leptocardia (Amphioxus) and of the Marsipobranchia 

 (Lampreys), which are not, with any certainty, 

 represented in a fossil state, the American scholar 

 studies the origin and the relations of the Fishes, 

 Batrachians, Reptiles, Birds, and Mammals. 



The Mammals are linked to the Theromorphic 

 Reptiles through the intermediary of the Mono- 

 tremata. The birds, or some of them at least, 

 seem to be derived from the Dinosaurian Reptiles. 

 The latter, in their primitive form of Theromorphs, 

 descend from the rachitomous Batrachians. The 

 Batrachians issue from a sub-class of the Fishes, the 

 Dipnoes, but the true primitive form is unknown to 

 us. The true Fishes, or Hypomata, have descended 



