78 PROCEEDINGS OF THE ACADEMY OF [Feb., 



OXYRHOPUS TRIGEMINUS Dumeril and Bibron THE TYPE OF 

 ERYTHROXYRHOPUS gen. nov. 



BY J. C. THOMPSON, SURGEON U. S. N. 



The classification contained in the Catalogue of the Snakes in the 

 British Museum will unquestionably remain our standard for years 

 to come. Nevertheless, when the suborder Serpentes has been 

 critically examined from the standpoint of comparative anatomy 

 along the lines suggested by Cope, there must be changes. 



When dissecting serpents, especially those that are now placed 

 in the larger genera, one sees species grouped that really should be 

 separated. In recording unusual structural conditions, in suggesting 

 new generic names, or in the regrouping of species, the following 

 routine will be observed: The specimens examined will be recorded 

 under the exact specific name employed in the Catalogue of the Snakes 

 m the British Museum, and where a new generic name is established, 

 it will be proposed provisionally, not for immediate use, but awaiting 

 a thorough examination of the subfamily to which it belongs. 



In studying Oxyrhoj)us trigeminus (Dumeril and Bibron) it was 

 found to possess an hemipenis without calyces and with an apical 

 disk. This is a condition widely different from Oxyrhopus cloelia 

 (Daudin) and Oxyrhopus petolarius (Linnaeus), in which the organ 

 has calyces and is without a disk. Two opisthoglyph serpents were 

 previously known with a similar organ. These, Erythrolarnprus 

 cesculapii (Linnaeus) and Philodryas elegans (Tschudi), have been 

 grouped by Cope in the subfamily of Enjthrolamprince } Oxyrhopus 

 trigeminus (Dumeril and Bibron) is believed to be worthy of generic 

 recognition. On the other hand, to alter a name well-established in 

 literature from the time of Dumeril and Bibron, should not be under- 

 taken without grave necessity. In this case the necessity will only 

 arise when the great majority of the Dipsadomorphince have been 

 examined anatomically, and one is in a position to propose a re- 

 arrangement of the species based upon a far wider knowledge of their 

 organs than is at present possessed. 



11900: Cope, Croo., Liz. and Sn. of No. Am., p. 1091. 



