CLASSIFICATION OF REPTILES 15 



structural characters of different groups of organisms quite equally. 

 The absence of a molar tooth in a mammal would ordinarily indicate 

 a genus, the absence of a tooth in a reptile might not indicate even a 

 variety or a race. Whence it follows that classification of organ- 

 isms is not and never will be an exact science. The value of char- 

 acters used in classification is very unequal, as we have seen. No 

 two persons see these characters from the same viewpoints, and in 

 consequence no two persons whose opinions are worth while ever 

 wholly agree as to classification. 



The following scheme differs only in minor details from the 

 more conservative of the generally accepted views, and those 

 differences are, for the most part, the writer's own opinions, to be 

 taken for what they are worth. It may be said decisively that 

 no classification of the reptiles into major groups, into super- 

 families or subclasses that has so far been proposed is worthy of 

 acceptance; there is no such subclass as the Diapsida or Synapsida, 

 for instance. And we have very much more to learn about the 

 early reptiles before any general classification of the reptiles can be 

 securely founded. It is very probable that the primary radiation of 

 the reptiles into the various lines of descent, into its main branches, 

 occurred much earlier than we have been disposed to believe ;^ that 

 before the close of Paleozoic time, perhaps before the close of the 

 Carboniferous, all the great groups of reptiles had gone off from the 

 main stem, and that since then only smaller and smaller branches 

 have appeared. There have been no new orders of reptiles in all 

 probability since Triassic times, and perhaps none since Permian. 



Taxonomists are often disposed to cut the Gordian knots of 

 relationships by raising the ranks of the animals they study to 

 independent positions. More than thirty independent orders of 

 reptiles have been proposed by different students, and quite as 

 many of mammals and of birds; possibly after more forms have 

 been discovered there will be as many proposed for the amphibians. 

 Sometimes, indeed, it is better to make such independent groups 

 than to unite lesser ones on doubtful evidence. But the writer, 

 for one, believes that it is more worthy of the thoughtful scientific 

 student to seek for relationships than for differences. It is far 

 easier to destroy than to construct, to make new genera, families, 



