CADUCIBRAXCHIATA. 33 



a. Two series of teeth (canthus rostralis distinct): 

 no plantar tubercles : fourth toe with three phal- 

 anges; twelve costal furrows (species large.) 

 Vomerine series transverse or directed backwards: 

 muzzle prolonged considerably beyond nares: brown, 



marbled with dark brown tenebrosum. 



Vomerine series in two sigmoids, which converge in 

 advance of nares: muzzle shortly rounded from external 



nares : uniform black aterrimum. 



a. a. Two series of teeth: fourteen costal grooves: 

 fourth digit with four phalanges. 

 Teeth arched between inner nares: head one-fourth to 

 groin (in small sp): eye one-half width between canthus: 

 muzzle broad: outer nearer than inner nares: brown, 

 with a series of lighter «pots on upper part of sides: be- 

 low yellowish: muzzle and tail marbled with the same. 



Texanum. 

 IV. Series of teeth not extending beyond inner mar- 

 gin of nares: lingual plicae radiating from a median lon- 

 gitudinal furrow of the tongue: no distinct parotid mass 

 (species small.) 



a. Two series of teeth (no canthus rostralis): fourth 

 toe with four phalanges. 

 Mandible shorter than muzzle: head elongate, width 

 between eyes behind equal from same to nares: width 

 of head 6.5 times in length to groin: black, with numer- 

 ous grey annuli on body and tail cingulatum. 



Mandible longer than muzzle: head short, broad: 

 width between the eyes behind equal from same to end 

 of muzzle: body stouter: width of head 6.5 to 7 times 

 in length to groin; lead-colored with a few grey shades 

 below microstomum. 



