258 TROPICAL MEDICINE AND HYGIENE 



"viperine element," which in large doses may cause intra- 

 vascular clotting, though it has no haemolytic property. 



(c) Hemibungarus. This genus includes slender, bril- 

 liant snakes, with a good deal of red in their colouring. 

 One species occurs in the hills of Southern India, the 

 other three belong to the tropical Asiatic islands of the 

 Pacific. 



(d) Callophis in form and colouring resembles Hemi- 

 bungarus. The species, five in number, are distributed 

 in the Eastern Himalayas and Indo-China, and in the 

 hills of Southern India and the Malay Peninsula. 



(e) Doliophis. The species of this genus differ from 

 Callophis only in having very greatly elongate poison 

 glands. They are found in Burma, Indo-China, and the 

 Malay Peninsula and islands. 



The genera and principal species of Asiatic Viperince 

 are the following : 



(a) Vipera. The head is broad, and is covered either 

 with small scales alone (Indian species), or with scales 

 and some small shields ; the neck is narrow ; the eye 

 is separated from the labial shields by small scales, and 

 the pupil is vertical. The nasal shield is either in contact- 

 with the rostral shield, or is separated by a naso-rostral 

 shield. The keels of the scales have a sharp, entire edge ; 

 the ventral shields are simple. The tail is short, with 

 the sub-caudal shields in two rows. True vipers are 

 found over the greater part of Asia; the most notorious 

 species is Vipera russellii, which occurs all over India, 

 from the Himalayas to Ceylon, also in Burma, Siam, and 

 Sumatra. V. russellii, the Daboia or Tic Polonga, is a 

 snake of considerable girth, and may attain a length 

 of 5^- ft. It is surly and sluggish, but is fierce when 

 disturbed. It is bright reddish-brown in colour, with 

 three longitudinal series of large, black, white-edged ovals 

 or rhombs ; the belly is light, and often spotted with 

 black. It is a dangerous snake, its venom being power- 

 ful and causing intravascular clotting in large doses, 

 and active haemolysis when absorbed slowly. It is a 

 snake that is often found near dwelling-houses. 



