CERASTES AND ECHIS. 85 



colder part of the year. It is, therefore, only in the hottest summer 

 months that the traveller is exposed to the danger of being bitten." 

 Dr. Gray refers doubtfully to this genus both the Echid?ia i?ior7iata 

 (Fig. 21) of Sir A. Smith, and the E. mauritanica of Dumeril aud 

 Bibron, from Algeria ; likewise a Peruvian species named Echidna 

 ocellata by Tschudi, which is the only known instance of a member 

 of this family inhabiting the New World. The appellation Echidna, 

 however, belongs properly to the Porcupine Ant-eaters, of the class 

 Mammalia. 



The species of Cerastes and of Echis have the nostrils much 

 smaller than the preceding, and are Vipers of less formidable size. 

 In the two species of Cerastes, or Horned Viper, the eyebrows of 

 the male bear commonly a sort of horn. C. Hasselquistii is com- 

 mon in Egypt ; and the other, C. Richii, inhabits Tripoli. Of Echis 

 there is one species in Egypt and North Africa, E. arenicola; and 

 another in India, E. cari?iata. The latter grows to about twenty 

 inches long, of which the tail measures two inches and a third. 

 These Vipers commonly lie half-buried in the sand, which they much 

 resemble in colour. They feed upon Centipedes (Scolopendra), and 

 no case is known of their bite having proved fatal. 



The remaining Viperidce have the head more or less shielded. 

 They are divided by Dr. Gray into Vipera (with two European 

 species, not found in Britain — V. aspis from the Alps, and V. 

 ammodytes from the countries bordering on the Mediterranean) ; 

 Pelias, which contains only the common British Adder, P. berus; 

 Sepedon, with one species only, from South Africa, S. hcemachates ; 

 Causus, with also only one African species, C. rhombeatus ; and 

 finally Acanthopis, founded on the Death Adder of the Australian 

 colonists, A. antarctica, which is the only member of the family 

 ViperidcB known to inhabit Australia, where the poisonous Colubrine 

 Snakes are so numerous. It is also the only known species the 

 scales of which are smooth or not keeled. It seldom exceeds thirty 

 inches in length, and varies a good deal in colour. Like other 

 Viperidce, it is sluggish in its movements, but when irritated it flattens 

 itself out generally in the form of the letter S, turning round to one 

 side or the other with astonishing rapidity, but never jumping at its 

 enemy or throwing itself backward, as the Puff Adders are described 

 to do. The Death Adder is found in almost every part of Australia 

 northward of the thirty-sixth parallel of south latitude.] 



The Common Adder {Pelias berus, Fig. 22), is not improbably 

 the "e X is of Aristotle, and the Vipera of Virgil, as it is the Manasso 

 of the Italians, the Adder of the country-people in England and 



