1886.1 **o5 [Cope. 



a. Nasal plate single. 



No preocular; no loreal Calamelaps* Gthr. 



A preocular ; rostral not prominent Elapomorphw \ Wieg. 



A preocular ; rostral prominent Ogmius Cope. 



aa. Two nasal plates. 

 j3. Two anal scuta. 



No preocular ; a loreal Enulins% Cope. 



A preocular ; no loreal Tantilla% B. & G. 



A preocular and loreal, tail smooth Hydrocalamus Cope. 



A preocular and loreal, tail short, rugose Procinura Cope. 



/?/?. One anal scutum. 



A loreal and preocular ; tail smooth ScolecopMs Cope. 



II. Posterior maxillary teeth smooth. 

 * Subcaudal scuta. 

 f Internasals united. 



Scales smooth Aspidura Wagl. 



Scales keeled Haplocereus Gthr. 



ff. Internasals and prefrontals distinct. 

 a. Rostral not produced. 

 Postoculars not distinct from temporals ; one nasal ; loreal joined to pre- 

 ocular Achalinus Pet. 



Postocular, preocular, and two nasals Mapops\\ Gthr. 



aa. Rostral produced. 



Two nasals and a loreal and preocular RhinocMlus B. & G. 



** Subcaudal scutella. 

 f Nasal scuta well developed. 

 \ No internasal scuta. 

 || Rostral plate produced. 

 Prefrontals separated by rostral ; nasals and first labial confluent 



Ficimia Gray. 

 Prefrontals in contact ; nasal distinct ; rostral little produced 



Conopsis Gthr. 



Rostral much produced Rhynelionyx*^ Pet. 



HI Rostral not produced. 

 Nasal confluent with first labial ; preocular and loreal distinct 



Sympholis** Cope. 



Nasal distinct ; loreal and preocular united Geophidiumf^ Pet. 



XX One internasal scutum. 

 || Prefontals united. 



Rostral much produced LigonirostraXX Cope. 



HI Two prefrontals (rostral not produced). 



* Mlcrelaps Bcettg. % Xenoealamus Gthr. 



■f- Urobelus Rhdt. ** Chilorhina Jan. 



% Not of Bocourt Miss. Sci. Mex. ft Xylophis Bedd. 



I Homalocranium D. & B. JJ Teninorhynchus Smith. 



1 Pariaspis Cope. 



