GEOGRAPHICAL DISTRIBUTION 259 



(b) Echls differs from Vipera chiefly in having serrated 

 keels on the scales of the sides of the body ; these scales 

 are also smaller than those of the back, and they point 

 downwards. The sub-caudal shields are in a single row. 

 Two species of this genus are known, namely, Echis cari- 

 nahis and Echis coloratus. (i) E. carinatus, the Phoorsa 

 or Kupper, is a small snake of a most angry and tierce 

 disposition. Its colour is greyish- or reddish-brown, with 

 one or more longitudinal series of white, dark-edged spots, 

 or sometimes with a white, wavy stripe along either side ; 

 there is often a white cross or " broad-arrow " on the head ; 

 the belly is white, usually with dark speckles. Besides 

 having an extended range in Northern Africa, it is found 

 in desert tracts all over South-western Asia, from Arabia 

 and Persia to Cape Comorin, occurring in hundreds in 

 certain places. It is a snake of deserts and rocky places, 

 and is likely to turn up in tents and on camping-grounds. 

 Its venom is very active, in the same way as that of 

 Russell's viper. (2) E. coloratus is found in Arabia, Syria 

 (and Egypt). 



(c) Pseudocerastcs chiefly differs from Vipera in having 

 a series of small scales between the nasal and rostral 

 shields. One species is found in Persia and Baluchistan ; 

 it has a scaly tubercle above either eye. 



(d) Eristicophis is another desert snake, differing from 

 Vipera chiefly in having a sharp keel or riclge on either 

 side of the ventcal shields. One species is known from 

 Baluchistan. 



(e) Azemiops has a head like a harmless Colubrine, 

 covered with large symmetrical shields, and furnished 

 with a loreal shield. One species is known from the 

 hills of Upper Burma. 



Other Viperince which extend into South-western Asia 

 are the African genera (see below), Bitis, Cerastes, and 

 Atracaspis. 



The Asiatic Crotalina, or loreal-pit-vipers, belong to 

 the following genera : 



(a) Ancistrodon. Though the head is shaped like that 



