384 



NA TURA L HIS TOR Y. 



their mothers. When these sea-snakes are removed from the water, they 

 seem to lose all their powers. It Mould appear that then their vision 

 becomes indistinct, and they are almost perfectly helpless. Attempts 

 have been made to keep them in aquaria; but the result has not been 

 the one desired. They seemed to lack some essential, and in a few days 

 all were dead. 



The remaining poisonous serpents are those already mentioned as pos- 

 sessing fangs eapable of erection and depression. When not in use they lie 



Fio. 340. — Sea-snake {Hydrophis). 



folded in the roof of the mouth, where they are concealed by two folds of 

 skin ; but when the snake strikes, they are thrown out. The blow, by 

 the intervention <>i' a series of bones, presses the poison-sac, causing a drop 

 or two of the poison to flow down through the hole in the fang. Still, it is 

 not necessary to strike to have the poison flow, for the observation has 

 been repeated many times that the animals can spirt it out to a little dis- 

 tance, without the lightest attempt at a blow. 



This snake-poison is rather peculiar in its action. It is harmless, or 

 nearly so, when swallowed, as the digestive juices seem to destroy its 



