105 



HETERODON NIGER.— Ca/e%. 



Plate XXIII. 



Characters. Head flattened, triangular, covered with plates in front and with 

 scales behind; snout pointed, and turned upwards at the tip; whole animal black 

 above, and bluish slate-colour below. PI. 127, sc. 50. 



Stnonymes. Black viper, Catesb., Carolina, vol. ii. p. 44, pi. xliv. 

 Scytale niger, Baud., Hist. Nat. des Rept, toni. v. p. 341. 

 Coluber cacodemon, Shaw, Gen. Zool., vol. iii. p. 377, pi. cii. 

 Pelias niger, Merrem. 



Coluber thraso, Harl., Med. and Phys. Res., p. 120. 

 Scytalus niger, Harl., Med. and Phys. Res., p. 130. 

 Heterodon niger, Troost, Ann. Lye. Nat. Hist. N. Y., vol. iii. p. 186. 



Description. The head is large, flattened, triangular; broader behind, narrow 

 and pointed in front, covered with scales posteriorly and with plates anteriorly. 

 The vertical plate is pentagonal, broadest in front. The superior orbital are 

 irregularly quadrilateral, broadest behind, with their outer margins projecting. 

 The occipital plates are rhomboidal; the frontal elongated and pentagonal; the 

 anterior frontal triangular, their bases inwards, and their apices reaching almost 

 to the nares; between their bases is an additional long narrow plate, elevated 

 above to form a ridge. The rostral plate is triangular, the base directed down- 

 wards, the apex upwards and pointed, with an elevated ridge on its upper surface. 

 The nasal plates are two; the anterior is round in front and above, and concave 

 behind; the posterior is narrow and lunated in front, to complete the opening of 

 the nostril. The anterior orbital plates are four in number, and nearly quadri- 

 VoL. II.— 14 



