GENERAL CLASSIFICATION OF POISONOUS SNAKES 5 



sea, near the shore, with the exception of the genus Distira, which 

 is met with in the fresh water of a lake in the Island of Luzon, 

 in the Phihppines. They are frequently found in very large 

 numbers in the Indian seas and throughout the tropical zone of 

 the Pacific Ocean, from the Persian Gulf to the west coast of the 

 American Continent, but they are entirely absent from the West 

 Coast of Africa. 



B. The ElapincB (land-snakes), with a cylindrical tail, and 

 covered with smooth or carinate scales. These serpents are fre- 

 quently adorned wath brilliant colours. Some of them (belonging 

 to the genus Naja) have the faculty of expanding the neck in the 

 shape of a parachute, by spreading out the first pairs of ribs when 

 they are alarmed or excited : the breadth of the neck then greatly 

 exceeds that of the head. They are distributed throughout Africa, 

 Asia, and North and South America, and are also found in Australia, 

 where almost all the snakes that are known belong to this sub- 

 family. 



The Family Viperid.e is characterised by a triangular head, 

 which is widened posteriorly, and by the general aspect of the 

 body, which is usually thick-set and terminated by a short tail. 

 The bones of the face are movable. The preefrontal bone is not 

 in contact with the nasal ; the maxillary is greatly shortened and 

 may be articulated perpendicularly to the ectopterygoid ; it bears 

 a pair of large poison-fangs, one on each side, and these are always 

 accompanied by several teeth to replace them, folded back in the 

 gum ; these latter teeth come in succession to take the place of 

 the principal tooth, when this is broken or falls out of itself when 

 the snake sheds its skin. 



The poison -fangs are not grooved, as in the Proteroglyplious 

 Coluhridce ; they are pierced by a perfectly formed canal, the upper 

 end of which inosculates with the efferent duct of the corresponding 

 poison-gland, while its lower extremity opens to the exterior a little 

 above and in front of the tip. The latter is always very sharp. 



