THE POISONOUS SNAKES OF INDIA. 41 



Colour, — Head and neck black except for a yellowish oblique occipi- 

 tal streak. Dorsally pur[»l:sli-brown, reddish-brown, or red, with 3 or 

 5 longitudinal series of spots which in some specimens are confluent, 

 and form lines. Belly uniform red. 



GROUP 4.— THE PIT-VIPERS. 



Identifij^at'On. — (1) Tail round. (2) A ccmspicuous opening zn 

 the side of the face between the e>/e and the nostril {the Ureal pit) 

 {see Fig. U B). 



This very disrinctive character is peculiar to this subfamily of vipers. 

 In spite of the fa^t that many membars of this subfamily (Crotalinae) 

 attain formidable proportions, »nd almost all are endowed with remark- 

 ably large poison fangs, the numorous accounts of bites inflicted by 

 them to be fount in scientific and other journals concur in showing 

 that death is an exceedingly rare event. My own experience, supported 

 by that of many of my fri^^uls, who have favoured me with letters on 

 this subject, entirely confirms the foregoing. A painful and swollen 

 condition locally and a very variable degree of constitutional disturbance 

 lasting in some instances for weeks passes on to complete recovery. 



These snakes are nearly all exclusively confined to hilly regions at 

 altitudes ranging between 1,5<'0 to 10,000 feet. The characters of the 

 shields, and scales upon which the classification of nearly allied 

 ophidian forms is so largely based, are sul»ject to very great inconstancy 

 in the members of this group, so much so that it is with the greatest 

 difficulty one can frame a lucid and really practical key to identify the 

 various species. I have, however, examined and re-examined most 

 critically all the spuciinens in the BriHsh Museum, and have only made 

 allusion to those peculiarities which are most constant, and which seem 

 to me of real practical use in identiHcation. 



Key for indeniificafion of Pit' Vipers. 



HEAD WITH LARGF SHIELDS (*ee Fi^s 24 to 27). 



Scales miiboly in 21 or 23 rows {see t'ig. 7) ... Ancistrodon hinalayanus. 



Scales midbody in 17 rows „ ^^ 



(a) Supraocular as broad as frontal, longer 

 than parietals Anchtrodon hyptiale. 



(6) Supraocular broader than frontal, shorter 

 than parietals ., inillardi. 



Scales midbody in 15 or 14 rows... Lachesis macrolepis. 



