Skull of Vipera lebetina. 
Divided into two subfamilies :— 
1. Viperine.—No pit on the side of the snout; maxillary not 
hollowed out above. 
2. Crotaline.—A deep pit on each side of the snout, between 
the nostril and the eye ; maxillary hollowed out above. 
Subfam. 1. VIPERINA. 
Viperoidea, part., Fitzinger, Neue Classif, Rept. p. 11, 1826. 
Viperide, art., Boie, Isis, 1827, p. 511. j 
Viperina, Bonaparte, Mem. Ace. Tor. (2) ii. p. 393, 1840. 
be ng part., Gray, Zool, Miscell. p. 68, 1842, and Cat. Sn. p. 22, 
Vipériens, Duméril, Mém. Ac. Se. xxiii. p. 528, 1853; Duméril § 
ibron, . Gén. vii. p. 1875, 1854. 
Atractaspidide, Giinther, Cat. Col. Sn. p, 239, 1858. 
i Causinw, Atractaspidins, Cope, Proc. Ac. Philad, 1859, 
Viperide, Giinther, Rept, Brit, Ind. p. 895, 1864, 
