Cope.l 480 [May 21, 



/S/9. No coronoid bone. 

 No supraorbitals nor postorbitals nor premaxillary teeth . Cliarinidie Cope. 

 ao. No rudiments of posterior extremities [Colubroidea.) 

 j3, Coronoid bone present. 

 No postorbital or supraorbital bones ; premaxillary teeth present 



Xenopeltidce Cope. 

 {3j3. No coronoid bone. 



v Postorbital bone produced over the superciliary region. 



No gastrosteges Acrochordidm Cope. 



Gastrosteges present , Nothopidce Cope. 



w Post orbital bone not extending over the superciliary region. 



3. Nostril in or between nasal plates Volubridce Auct. 



£ . Vertebral hypapophyses confined to the anterior part of 



the column Colubrince. 



££. Vertebral hypapophyses extending throughout the column 



Homalopsince Cope. 

 88. Nostril in the rostral plate Acontiophidw Gthr. 



V. Os maxillare horizontal, thickened in front, and not reaching the pre- 



maxillare anteriorly, and bearing a perforate tooth 



Proteroglypha. 

 a. Caudal hypapophyses bifid ; caudal neural spines and pleurapophy- 

 ses short. 



Postfrontal bones wanting; fang grooved Elapidce Cope. 



Postfrontals present ; fang grooved Nnjidm Cope. 



Postfrontals present ; fang not grooved Den draspid idee Gthr. 



aa. Caudal hypapophyses simple ; caudal neural spines and pleura- 

 pophyses elongate. 

 A postfrontal bone HydropMda Gthr. 



VI. Maxillary bone vertical, not reaching premaxillary, articulating with 



the prefrontal by a ginglymus, and to the ectopterygoid without 



imbrication, and bearing a perforated tooth Solenoglypha. 



Maxillary bone not excavated ; fang not grooved in front; no postfrontal 



bone Atractaspididce Gthr. 



Maxillary bone not excavated ; fang grooved in front ; a postfrontal 



Causidce Cope. 

 Maxillary bone not excavated ; fang not grooved ; a postfrontal 



Viper idee Gray. 

 Maxillary bone excavated by a large chamber ; fang not grooved in front ; 



a postfrontal Crotalidce Gray. 



In the following pages I present synoptical diagnoses of the genera of 

 the Ophidia arranged in key form. These are placed under subfumily 

 heads, which are not, with the exception of the Homalopsina 1 , defined. It 

 is not certain, therefore, that their contents are in all cases properly lim- 

 ited or distributed. It remains a desideratum to discover the characters of 

 the natural divisions of the Colubridffi, if any there be. The characters 

 presented by Dumeril and Bibron, and by Giinthcr, are important but in- 



