Vol. VII. September, 1904. No. 



BIOLOGICAL BULLETIN 



THE TEMPORAL ARCHES OF THE REPTILIA. 



S. W. WILLISTON. 



Students of herpetology are indebted to Professor Henry F. 

 Osborn for a careful taxonomic and morphological study ] of the 

 extinct reptilia, from which he has concluded that the class is 

 divisible into two distinct subclasses or phyla, which he has 

 called the Synapsida and Diapsida. The writer has studied his 

 paper with much interest and desires to acknowledge his indebted- 

 ness to it for many new ideas and stimulating suggestions, 

 though he is forced to differ from the author in some of his con- 

 clusions. A full discussion of this paper is not possible at the 

 present time, and the present communication, will, therefore, be 

 restricted to a discussion of the relations of the bones of the 

 temporal arches of the reptilia, relations which really lie at the 

 basis of any classification. 



I may mention, however, that I do not see my way clear to 

 accept the term Synapsida proposed by Professor Osborn for the 

 group of single barred reptiles, since this group really does not 

 differ in any essential respect from the Synaptosauria (in the wider 

 sense) of Fiirbringer 2 and differs from the Synaptosauria of Cope, 

 as most recently defined by him 3 chiefly in the inclusion of the 

 Cotylosauria. But, I believe that Cope was right in separating 

 the two groups, since he recognized, as does Osborn, the ances- 

 tral relations of the Cotylosauria to both the single and double- 

 barred reptiles. If all other reptiles are derived from them, and 



1(1 The Reptilian Subclasses, etc." Mem. Amer. Mus. Nat. Hist.,Vo\. I., p. 



45 1. 1903- 



2 Jena ZeitscAr., 1900. 



3 "The Crocodiles, Lizards and Snakes of North America," Rep. U. S. Nat. 

 Mus., 1898, p. 159. 



