The venom of this viper is terribly potent. According to Russell, a large dog exhibited symptoms of poisoning five minutes after being bitten. At the end of a quarter of an hour it lay down, uttering heartrending cries, began to breathe with difficulty and noisily, was seized with spasms of the jaws and cramps, and died in frightful agony less than half an hour after the wound was inflicted. Fowls in most cases die in less than two minutes. A horse succumbed in half an hour, and another in eleven hours. It appears that in India many cattle are killed by Daboias while grazing (_Fayrer_). (b) =Pseudocerastes.= (Fig. 29.) This genus is represented by a single species (_Pseudocerastes persicus_), which appears to be exclusively confined to Persia. The head is very distinct from the neck, and covered with small imbricate scales; the eyes, which are small, have vertical pupils; they are separated from the lips by small scales. The nostrils are directed upwards and outwards. The snout is very short and rounded. The cylindrical body has 23-25 rows of scales; 151-156 ventrals; 43-49 subcaudals. [Illustration: FIG. 29.--_Pseudocerastes persicus._ (After Duméril and Bibron.)] The coloration is gray or brown, with four series of large black spots, and the head exhibits two longitudinal black streaks behind the eyes. The belly is whitish, dotted with black. Total length, 890 millimetres; tail 110. (c) =Cerastes.= The vipers belonging to this genus are much more common in North Africa, and we shall therefore study them in conjunction with the African snakes. _Cerastes cornutus_ alone, the special habitat of which is Egypt, is sometimes met with in Arabia and on the eastern bank of the Suez Canal. (d) =Echis.= _Echis carinatus_ (the Phoorsa). (Fig. 30).--This viper is characterised by the subcaudal shields being arranged in a single row. It is savage and very aggressive, being always ready to attack. Its length does not exceed 600 millimetres at the most. The colour of the body is grey, more or less dark and adorned with streaks, spots, and dots of blackish-brown. The back displays yellowish-white wavy lines, forming X-shaped markings. The upper side of the head exhibits a yellow spot surrounded by brown, and other small black spots, the whole arrangement forming a fairly good representation of a cross. [Illustration: FIG. 30.--_Echis carinatus._ India. (After Sir Joseph Fayrer.)] This species is found in India, Persia, Baluchistan, Arabia, and Palestine; while, as we shall see, it also occurs in Africa. It is fairly common in the environs of Aden. In moving over the ground a peculiar sound is produced by the friction of its scales. It is capable of springing with great agility a fairly long distance on to its prey. When it believes itself in danger it coils up, doubling its body twice in the shape of a crescent, in the middle of which it places its head, ready to strike. Its venom is very rapid in taking effect. 2.--CROTALINÆ.