appellation _Echidna_, however, belongs properly to the Porcupine Ant-eaters of the class Mammalia. [18] In Chapman's "Travels in the Interior of South Africa" (vol. ii. p. 59), we read--"May 19th. I lost my best Dog, Cæsar. He had seized a large Puff-adder by the tail, and shook it. When the Snake was released it darted at the Dog's face, and having fixed its fangs in its cheek, stuck there like a Bull-dog until it was killed. The Dog only survived ten minutes."--ED. [Illustration: Fig. 22.--The Unadorned Puff-adder (_Clotho inornata_).] 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 common 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. carinata_. 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 _Viperidæ_ 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. hæmachates_; _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 _Viperidæ_ 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 _Viperidæ_ 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_), is not improbably the +Echis+ of Aristotle, and the _Vipera_ of Virgil, as it is the _Manasso_ of the Italians, the Adder of the country-people in England and Scotland, and the Vipère of France. It is found in all these countries, and in Europe generally. [Illustration: Fig. 23.--The Common Adder (_Pelias berus_).]