208 BACKBONED ANIMALS. 



ing in horny, button-like rattles (Fig. 248), incorrectly 

 supposed to indicate the age of the snake. The rattle 

 is sounded at the approach of danger. The bite of the 

 rattlesnake is often fatal if no remedy is at hand. They 

 hibernate in the winter, and the young have been seen 

 passing into the mouth of the mother for protection. 

 The fer-de-lance of the West Indies is deadly. It is 

 dark-yellow or brown, and attains a length of six feet. 

 It is viviparous, giving birth to fifty or sixty young. 

 Moccasins. Water-moccasins are common in the South- 

 ern States, and are much dreaded. They are about two 

 feet in length, dark brown in color, with transverse bars 

 of black, and are extremely vindictive. The copperhead 

 is also dreaded. Both have been observed to receive their 

 young into their mouths, and so protect them. 



VALUE. Rattlesnake-oil is valued, and crotalin is obtained from 

 the snake. Oil of the copperhead is also used in medicine. Rattle- 

 snake leather is used in bags, cases, etc. 



Sea-Snakes (Hydrophida). These snakes, fifty spe- 

 cies of which are known, are found in the Indian, China, 



FlG. 250. Platurus vulcanicus, a sea-snake living in the fresh-water lake 

 of Taal (Luzon), and having a paddle-like tail. (After Semper.) 



and Australian seas, and have been seen near Panama. 

 They only approach the shore to breed, and, with one ex- 

 ception (Fig. 250), are marine. They are extremely poison- 



