OPH1DIA. 



459 



In the group Venenosa, in which there are canaliculated 

 fangs placed in front of the superior maxillae with smaller solid 

 teeth behind them, are some of the most deadly of all living 

 serpents. One of the best known of these is the Hooded 

 Snake, or Cobra di Capello (Naja tripudians\ which is com- 

 monly found in Hindostan, and is the snake usually carried 

 about by the Indian snake-charmers. It varies from two to 

 six feet in length, and the neck can be extensively dilated, 

 covering the head like a hood. A nearly-allied species is the 

 Naja Haje (fig. 197) of Egypt. Also in this section are the 

 venomous Water-snakes (Hydrophidtz), which have a com- 

 pressed tail, and are adapted for an aquatic life. They mostly 



Fig. 198. A, Head of Colubrine Snake (Colubsrnatrix) ; B, Head of Viperine Snake 

 (Pelias bents) ; C, Head of Blind-worm (Ajtguisjragilis), one of the serpentifonn 

 Lizards. (After Bell.) 



frequent the mouths of rivers in droves, and they swim with 

 great grace and rapidity. 



A very good general character by which the Colubrine snakes 

 may be distinguished from the Viperine snakes, is in the shape 

 and armature of the head. In the Viperina, as before said, 

 the head (figs. 196, 198) is triangular, broadest behind, and 

 separated from the neck by a more or less marked diminution 

 in the diameter of this latter part. The scales, too, which 

 cover the head are of small size. In the Colubrine snakes, on 

 the other hand, the head is not markedly triangular, and gra- 

 dually tapers off into the neck, whilst the upper surface of the 

 head is usually covered with large shield-like plates or " scuta " 

 (fig. 198, A). 



DISTRIBUTION OF OPHIDIA IN TIME. The Ophidia are not 

 known to occur in any Palaeozoic or Mesozoic deposit. The 



