ARRANGEMENT OF TEETH AND FANGS.
The arrangement of the teeth and the presence or absence of fangs are of cardinal importance. Every poisonous Snake is provided with fangs, while, with one exception-and there may be others--that of Psammodynastes pulverulentus, innocent Snakes are free from such weapons. The manner in which the efficient and supplementary fangs are attached to the jawbone is well shown in A, B, C, whilst D demonstrates the mode in which the recurved teeth of an innocent Snake are fixed. The relations of the poison fangs and ordinary teeth are still further illustrated in the skeleton heads of the Russell's Viper (Daboia Russellii), Bungarus fasciatus, figured in Plate 20, and of the Cobra (Naja tripudians), in Plate 21, contrasted with the dentition displaying the simple fish-like teeth of the non-poisonous Dhamin (Ptyas mucosus) in Plate 21. The fangs are separately figured in A, B, C. These are either channelled into a tubular canal, as in the Daboia and Cobra, or only grooved as in the Hydrophis. It is through this tubular or grooved fang that the poison is injected from the poison-gland into the tissues of an effectively bitten animal or man.
