CEEASTES AND ECHIS. 91 



abled to destroy it without much risk. The Snakes of South 

 Africa, as of Europe, lie concealed in their holes in a torpid state 

 during the 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 Echidna inornata of Sir A. Smith, and the E. mauritanica of 

 Durneril and 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 Porcu- 

 pine Ant-eaters of the class Mammalia. 



The species of Cerastes and of Echis have the nostrils much 

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

 In the two species of Cerastes, or Horned Yiper, 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 Egj^pt and North Africa E. arenicola, 

 and another in India E. carinata. The latter grows to about 

 twenty inches long, of which the tail measures two inches and a 

 third. These Yipers 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 Viper a (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. haemachates ; 

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

 and finalty, Acanthopis, founded on the Death-adder of the Aus- 

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

 family Viperidae 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, 



