VERTEBRATA. 199 



ternally, or it is inflected on itself so as to form a tube ; the 

 poison-gland is at its base beneath the eye on each side. The bite 

 of a venomous serpent makes two punctured wounds, but from a 

 non-venomous serpent there will be probably two lines of punc- 

 tures. In this country we have only one venomous species, 

 whose bite is rarely attended with fatal effects. On the other 

 hand, in Hindostan the number of persons killed annually is esti- 

 mated by Sir J. Fayrer to be over 20,000 (Thanatoph. p. 32). 



The action of serpent-poison is neurotic, annihilating in some 

 unknown way the nerve-power. Serpents, it is said, are not 

 affected by their own poison. Ophiophagus elaps, the largest and 

 most venomous of them, feeds on other serpents only less dan- 

 gerous than itself. Hydrophidas are marine, but confined to 

 Indian seas. 



The most noted serpents are the rattlesnake ( Crotalus korridus), 

 the asp [of Cleopatra] ( Cerastes Hasselquistii, or Naia haje accord- 

 ing to Glaus), the puff-adder [of the Cape] (C'otho arietans), 

 viper or adder (Pelias berus), cobra (Naia tripudians), and the 

 snake (Natrix torquata). The coral-snake of Guiana is llysia 

 scytale. The largest snakes belong to the genera Python and 

 Boa. Eunectes murinus of the Amazon is over 20 feet long. 



The Ophidia, of which more than 900 species have been de- 

 scribed, are divided by Dumeril and Bibron into five suborders, 

 which may be tabulated thus : 



Mouth dilatable. 

 With poison-fangs. 



Fangs perforate SOLENOGLYPH A. 



Fangs grooved PROTEROGLYPH A. 



Without poison-fangs AGLYPHODONTIA. 



Mouth not dilatable. 



With anal spurs ANGIOSTOMATA. 



Without anal spurs OPOTERODONTIA. 



OPOTERODONTIA. Mouth small, not dilatable. Teeth in the 

 upper jaw only. No poison-fangs. 



The tail is short or none. The head is small, and the eyes are 

 rudimentary. There are no anal spurs. 



These are small worm-like animals, sometimes referred to the 

 lizards, living in burrows underground or under stones; they 

 feed on insects and worms. 



Typklopidce. 

 Stenostoma. 

 Typhlops. 



