in the Collection of the British Museum. 353 



I refer this species provisionally to Mizodon, although it dif- 

 fers in several points from the typical species of this genus, viz. 

 in the length of the tail, and in the entire anal shield. West 

 Africa appears to be inhabited by many Coronelline Snakes; 

 and before other additions to our knowledge of them have been 

 made (which we may shortly expect), it appears hazardous to 

 propose further generic divisions. 



Xenodon, Boie. 



This genus ought to be restricted to the South American spe- 

 cies with smooth scales. Having lately received a form with 

 twenty-one series of scales, from Kio Janeiro, and another with 

 seven labial shields fiom Central America, I was induced to re- 

 examine all our specimens, the number of which has been con- 

 siderably increased since the publication of the ' Catalogue of 

 Colubrine Snakes,' and I am now enabled to distinguish seven 

 species. Xenodon typhlus, L., differs from the others in having 

 the scales more uniformly rhombic and less imbricate. The 

 remaining six species may be distinguished as follows : — 



* None of the labial shields enter the orbit. 



Labials eight ; anal entire X. gig as, D. & B. 



** Only one labial enters the orbit. 



Labials seven ; anal bifid X. irregularis, n. sp. 



*** Two labials enter the orbit. 



Labials eight ; anal bifid. Ventral shields 

 131-144. Coloration uniform, or with 

 about eight very broad dark bands across 

 the trunk X. severus, L. 



Labials eight; anal entire; ventrals 141- 

 1,51. Eye large; crown of the head uni- 

 formly coloured. (This species appears to 

 be confined to the province of Bahia). . . X. colubrinus, Gthr. 



Labials eight ; anal bifid ; ventrals 163-1 74; (PL V. fig. E.) 



scales in twenty-one series ; trunk with 

 about twenty dark cross bands X. Neuwiedii, n. sp. 



Labials seven ; anal bifid or entire ; ventrals 

 144-157; trunk with about fourteen dark- 

 brown, black-edged cross bands, contracted 



in the vertebral line X.rhabdocephalus* . 



(PI. V. fig. B.) 



* Prince Maximilian of Neuwied has evidently represented two distinct 

 species under the name of X. rhabdocephalus. We preserve this name for 

 the more common species (Bahia, Pernambuco), figm-ed on plate 4 of the 

 10th part of the ' Abhildungen,' whilst plate 3 appears to be intended either 

 for X. colubrinus or X. Neuwiedii, probably for the former, although the 

 physiognomy of the snake is not well represented. 



