248 Trans. Acad. Sci. of St. Louis. 



''The following table of the superfamilies, families, and 

 subfamilies of snakes gives the essential characters by 

 which these divisions have been separated. There is still 

 considerable divergence in the opinions of authors con- 

 cerning the relative value of some of these divisions, but 

 in breaking up the aglypli and opistoglyph 'series' I 

 believe that a better recognition of the true relationships 

 of their component parts can be obtained." 



Synopsis of Supekfamilies, Families, and Subfamilies. 



Maxillary bone horizontal; no loral pit. Natricoideae. 



None of the anterior maxillary teeth grooved or perforated. 



Natricidae. 

 Hypapophyses present throughout the vertebral column. 



All maxillary teeth solid. Natricinae. 



Hypapophyses absent in posterior dorsal vertebrae. 



All maxillary teeth solid. Coronellinae. 



Posterior maxillary teeth grooved. Boiginae. 



Anterior maxillary teeth grooved or perforated. 



Elapinae. 



Maxillary bone vertical. Crotaloideae. 



A deep loral pit. Crotalidae. 



"The above sj^nopsis is chiefly based upon characters 

 which either require more or less dissection or examina- 

 tion of the posterior maxillary teeth. The latter often 

 presents difficulties, and in some cases must be resorted 

 to in order to obtain absolutely reliable identification. 



"The examination of the dentition must be made very 

 carefully in order to avoid mistakes. The safest way 

 is probably to dissect out one of the maxillary bones. 

 This can be done very easily by running the point of a 

 sharp knife between the supralabials and the underlying 

 bone, cutting the tissue along the whole length of the lat- 

 ter. By forcing the point of tlie knife over the upper 

 edge of the bone in the region of the eye the bone can 

 be easily lifted up and the connecting ligaments severed. 

 The adherent tissue may be carefully removed, though in 

 most cases it is sufficient to let it dry. The teeth can now 

 be examined convenient! v. Care must be had not to mis- 



