316 REPTILES OF THE WORLD 



have examined, the maxillary of the present reptile is 

 reduced to a small, vertical, movable bone on each side 

 of the anterior part of the head and bearing an enor- 

 mously elongated, caniculated fang, provided with a 

 narrow orifice at the tip like a hypodermic needle. Con- 

 necting with each maxillary is a bone extending 

 from the rear of the head, its function lever-like in rais- 

 ing or lowering the fang at the will of the snake. Here 

 we find several differences from the formidable elapine 

 snakes, thus: — (1) There are no teeth in the upper 

 "jaw," except the two rows of palatine teeth and the 

 pair of huge, venom-conducting fangs; most of the 

 elapine snakes have a short row of small teeth behind 

 each fang. (2) The fangs of the Vipers, rigidly 

 attached to movable bones, fold flat against the roof of 

 the mouth when the jaws are closed. 



By far the greater number of Viperine snakes are 

 thick-bodied, with a distinct flattened head, while the 

 eyes have a cat-like pupil. They exhibit the outlines 

 popularly accredited to poisonous snakes and are mark- 

 edly slower in their motions — except in striking — than 

 the elapine snakes. As a great number of the species 

 have the head covered with small scales in place of reg- 

 ularly-arranged shields, they may be told almost at a 

 glance. Still there is considerable variation in form 

 from the slender tree vipers to the hideous-looking 

 adders of Africa. A certain proportion of the species 

 have a comparatively slender body and a head provided 

 with regularly-arranged shields, as noted among the in- 

 nocuous and the venomous Colubridce. There is no pos- 

 sibility of constructing a popular chart key that will ena- 

 ble the student to distinguish such species. Locality is a 

 factor of great importance and the writer has endeav- 



