ARTICLE III. 



THE CLASSIFICATION OF THE OPHIDIA. 



BY E. D. COPE. 

 Read before the American Philosophical Society, September 21, 1894. 



Owing to the absence of limbs and other points in which diversity is usually 

 apparent, the classification of the snakes has always presented difficulties to the zool- 

 ogist. An order which dates from Cretaceous time and has spread over the entire 

 world, must have differentiated in structure, if its history has been like that of other 

 orders of Yertebrata. Yet the researches of anatomists have only resulted in finding 

 characters which define five' suborders, and about a dozen families. Of the natural 

 groups thus defined, one family, the Colubridse, embraces three-fourths of the species, 

 and is of cosmopolitan distribution. So long as this was the principal result attained, 

 it remained clear that the stronghold of the order had not yet been taken. 



The primary divisions above referred to are defined by peculiarities of the skele- 

 ton, and these were mostly originally described by Johannes Miiller. In the prepara- 

 tion of their Herpetologie Generale, Dumeril and Bibron made a full study of the 

 dentition. The results they obtained were important, but they were very far from 

 expressing an exact and clear-cut classification. The greatest defect of their defini- 

 tions based on the teeth is that they too often fail to define. One type passes by easy 

 gradations into another, so that in many cases it is impossible to determine what type 

 a given dentition represents. In most cases it is clear that, among Colubrid snakes at 

 least, no higher groups than genera can be predicated on dentition, and frecpiently not 

 even these. Under snch circumstances further structural characters had to be sought 

 for if we are to have any clear idea of the affinities and phylogeny of this curious 

 branch of the Eeptilia. In any case, no systematic arrangement can be regarded 

 as final until the entire anatomy is known. 



In 1864 * I pointed out that certain snakes, notably the water snakes, have the 



* Proceedings Academy of Natural Sciences, Philada. 



