BATRACHIANS AND KEi'TlLES, CENTRAL AMEBIC A AND MEXICO. 51 



CHARINID.E. 



Head scutate above ; scales smooth ; tail uot prehensile ; palatine teeth. 



Charina^ Gray. 



ACKOCHORDID/E. 



Body compressed, acute below Chersydrus Cuv. 



Body round, flat below Acrochordiis Ilornst. 



NoTIIOPSIDiE. 



Scales above granular, with rows of tubercular scales ; urosteges simple ; no frontal 



or parietal plates Xenodermus Rhdt. 



Scales squamous ; urosteges double ; head scaly, with frontal and parietal plates. 



Nothopsis Cope. 



COLUBRIDjE. 



Head conic, not distinct from the body, which is cylindric and rigid. ..Calamarin/E. 



Head slightly distinct, short; teeth entire, not enlarged in front CoRONELLiNiE. 



Head similar to last ; posterior tooth grooved Scytalin.e. 



Head more distinct and elongate, body and tail longer ; teeth entire, not longer in 



front Natricin.e. 



Like the last, but grooved teeth posteriorly Philodryadin^e. 



Very slender^ x>upil horizontal; grooved teeth Dryophidin.e. 



Less slender; not compressed ; middle teeth elongate, posterior teeth grooved. 



PSAMMOrniPIN^. 



Anterior maxillary and mandibular teeth enlarged Lycodontin.e. 



Anterior teeth not abruptly enlarged, posterior grooved ; head wide, very distinct, 



body compressed Dipsadin^e. 



Anterior teeth not abruptly enlarged, the posterior Weak and not grooved ; head very 



distinct from the body, which is compressed ; no oesophageal 



teeth LEPTOGNATI1IN.E. 



Maxillary teeth few and rudimental ; body slender ; hypapophyses piercing throat, 

 and capped with enamel Dasypeltix.e. 



Hypapophyses spinous to caudal region ; anterior teeth not enlarged ; body not slen- 

 der; head distinct Colubrinoe. 



CALAMARIN^. 



I. Posterior maxillary tooth grooved. 

 * Subcaudal scuta. 



One nasal; anal undivided UriccMs"- Vat. 



Two nasals; anal divided - Cercocalamus Gthr. 



** Subcaudal scutella. 

 t No iuteruasals. 



One nasal, no preocular Ambhjodipsas Fet. 



One nasal, a preocular Aj^ostohpis Cope. 



tt Two internasals; prefrontals united together. 



One nasal; a preocular P/iaZo/r/'s Cope. 



ttt Internasals united with nasals. 



Postnasal distinct, anal divided StenorUna D. & B. 



tt^t Two internasals and two prefrontals. 

 a. Nasal plate single. 



No preocular; no loreal Calamelapa'' Gthr. 



A preocular ; rostral not prominent El apomorphus* Wicg. 



1 Wcnona B. & G. ^ Micrelaps BoBtg. 



^Polemon Jan. * Urobelus Khdt. 



