THE SNAKES 329 



captives. They feed well enough for a few months, 

 then die of various ailments — enteritis, diseases of the 

 lungs or suppurative disorders of the mouth-parts. 

 Eight specimens were at one time exhibited in the New 

 York Zoological Park. They would not feed unless 

 the temperature of their cage was over 75° Fahrenheit, 

 continually clustering on the perforated copper sheath- 

 ing in the front of their cage, which metal was directly 

 over the heating pipes. Like all desert vipers, they were 

 continually seeking to throw sand over their backs, thus 

 hiding their bodies. If the cage were to be provided 

 with several inches of fine sand, nothing would be seen 

 of the snakes during the day but the tops of their heads. 

 In shovelling sand the reptile flattens the body to such 

 an extent, the lower edge acts as a scoop, then by a 

 remarkable series of wave-like motions travelling the 

 length of the body, on either side, the snake sinks into 

 the sand or works this over its back. To provide for 

 this sand-loving life the eyes are placed near the top 

 of the head, as with some water snakes (Helicops), but 

 this character is more pronounced with the Common 

 Sand Viper, C. vipera, of northern Africa. It is with- 

 out horns, but otherwise much like the preceding species. 

 A flourishing colony has also lived in the Zoological 

 Park. The specimens alternately endeavored to shovel 

 sand or move rapidly about the cage in a bewildering 

 series of loops — the reptile not actually crawling, but 

 throwing out lateral loops, one after another, in a fashion 

 that imparts an agile walking motion. The arrival of 

 these vipers was attended with a great surprise to the 

 writer, who momentarily thought he had discovered a 

 "new species." 



When the vipers arrived at the Park, specimens of 

 the closely-allied horned species, C. cornutus, were mixed 



