1100 REPORT OF NATIONAL MUSEUM, 1898. 



aaa. Fusiform. 



yS. A loreal plate. 



Tail abbreviated, rough Procinnra Cope' 



Tail normal Scolecophis Cope 



P/3. No loreal. 



Two pairs of genials Tantilla Baird and Girard 



One pair of genials Pogonaspis Cope 



III. Caliculate and capitate (Capitati). 



Calyces numerous; colubriform; anal double Sibon Fitzinger 



IV. Spinous to apex (Spinosi). 



Fusiform ; rostral prominent ; anal divided Ogmiiis Cope 



V. Apex with longitudinal plicae ; calyces few and irregular. 



Spines few ; head very distinct ; anal double Trimorphodon Cope 



The groups of Dipsadinae, from 1 to IV, inclusive, correspond in penial 

 characters to the groups similarly numbered in the Dromicinjie and 

 Scytalina3, respectively. 



I have not been able to examine the penial structure of some of the 

 genera of this subfamily which inhabit the Old World, so I give a 

 synopsis of the genera as otherwise defined : 



A. Head shorter and more obtuse; very distinct. 



I. Subcaudal scuta entire. 



Parietal plates replaced by scales ; other plates iwTmal.Pythonodipsas Giinther 



II. Subcaudal scutella divided. 



a. No teeth anterior to the grooved maxillary. 



Scales smooth Opisthoplus Peters 



aa. Median maxillary teeth not much shortened. 



Nostril large, between two nasals and the internasal; vertebral scales 



larger Bhinobothryum Wagler 



Two nasals inclosing nostril; body elongate, compressed, anal entire; 



vertebrals generally larger Dipsas Laureutis^ 



Two nasals inclosing nostril; body less compressed ; anal double; verte- 

 bral row not larger ; one loreal Sibon Fitzinger* 



No nasal; vertebrals equal Hemidipsas Giinther* 



aaa. Median maxillary teeth shortened. 



Two nasals and two or more loreals ; anal double ; vertebrals equal. 



Trimorphodon Cope 

 AA. Head very elongate ; muzzle produced. 



I. Middle maxillaries not elongate; posteriors grooved. 



Scales keeled Dryopliis Boie 



Scales smooth Dryinua Wagler 



II. Middle maxillaries elongate; posteriors grooved. 



a. An elongate nasal appeudage. 



Pupil horizontal Passerita Gray 



aa. No elongate nasal appendage. 



A loreal plate; prenasals joined on the middle line Gepliyrinns Cope 



A loreal plate ; nasals not joined Trac/ops Wagler 



No loreal plate ; nasals separate Tropidococcyx Giinther 



^ Elapomorphus, Phalolris, and ApostoJepis probably belong here. 

 ^Boifja Fitzinger; Triglyphodon and Rimantodes Dum6ril and Bibron; JEudipsaa 

 Giinther ; Toxicodryas Hallowell. 

 * Crotaphopeltia Fitzinger. 

 ■• Eumeaodon Fitzinger. 



