956 



REPORT OF NATIONAL MUSEUM, 1898. 



II. Anterior maxillaries isolated. 

 a. Subcaudals in two rows. 



(5. Nareal region with a pit. 



Scales smooth ; anal entire Bothrolyciis Giinther. 



/3. No nareal pit. 



y. Longest teeth at front of maxillary. 



Scales keeled ; two nasals ; a loreal Ophites Wagler. 



Scales smooth ; two nasals ; a loreal Lycodon Boie. 



Scales smooth; two nasals ; no loreal. Tetrafjonosoma Giinther. 



Scales smooth ; one nasal ; a loreal Leptorhytaon Giinther. 



aa. Subcaudal plates in one row. 



Scales keeled Cercaspis Wagler. 



Scales smooth Cyclocorua Dumeril and Bibron. 



The geographical distribution of these genera is as follows : 



Paleotropical. 



Palearctic. 



Nearctic. 



Neotropical. 



Ethiopian. 



Dinodon 



Ophites 



Lycodon 



TetragoDosoma . 

 Lei)torhy taon . . . 



Cercaspis 



Cyclocorus 



Lycodryas. 



Boiidon. 



Bothrophthalmus. 



Lycophidiurn. 



Horiuonotus. 



Laniprophis. 



Simocephalue. 



Holuropholis. 



Bothrolycus. 



NATRICIN^. 



We have here a well-defined and homogeneous group, which is dis- 

 tributed in the northern continents and the oriental region. A spe- 

 cies is said to be found in the Ethiopian, but I have not yet been able 

 to examine the penial characters. 



I. Sulcus undivided, 



a. Two large apical papillae. 



Scuta normal ; anal entire Tropidoclonium Cope. 



aa. No apical papillie. 

 fJ. No preocular plate. 



One iuternasal; anal divided; scales keeled. ..Raldea Baird and Girard. 



Two internasals; anal divided; scales keeled Amphiardis Cope. 



Twointernasals; anal divided; scales smooth . Virginia Baird and Girard 

 ftf5. Preocular present. 



No loreal; anal divided; two internasals Storeria Baird and Girard. 



A loreal ; anal entire; two internasals Eutwnia Baird and Girard. 



A loreal ; anal undivided ; one internasal Liodytea Cope. 



A loreal; anal divided; scale-pits double NaMx Laurenti.' 



A loreal ; anal divided ; no scale-pits Seminatrix Cope. 



XL Sulcus bifurcate; (hemijienis furcate). 



Two apical papilla- ; plates as Nalrix Ceratophallus Cope. 



No papillae ; plates as Natrix Bothrodytes Cope.^ 



No papilliB ; one prefrontal plate , Trimerodytes Cope.' 



' Including Amphiesma Dumeril and Bibron. 



2 Including Diplophaiu'l}i8 Cope. 



3 Proc. Acad. Nat. Sci. Phila., 1894, p. 426. 



