'60 THE POISONOUS SNAKES OF INDIA. 



must admit that in a fe\v cases, at leost, the cobtu is not recognised, 

 und sometimes a harmless snake is mistaken for it. Nicholson's footnote 

 on page 151> of his work on Indian snakes is a striking corroboration of 

 my own experience. He says : " I have seen an Englishman, considered 

 " rather an authority on snakes, declare that a Ptyas mucosus 

 " (now Zamenis vwcosus) just brought to mo was a cobra ; he even 

 " pointed out the poison-fangs." So long as people continue to be 

 guided by these faulty characters in diagnosis, mistakes are sure to 

 occur. 



Now there are one or two very distinctive peculiarities about the 

 scales of a cobra which if looked for should place its identity beyond 

 question. These are as follows : — 



Tlie prccooulat' shield touches the hilernasaV* (see Pra. and Int., iig. 

 Iti B). In only two other snakes is this relationship to be found, v«c., 

 in XylapMs pei-roteti, a small harmless snake peculiar to the hills 

 of Southern India, and the rare Amblt/cephahis muntkola. In both 

 the ord supralabial shield does not touch the nasal. 



Betioeen the 4:th and 5th infralabial shields a small luedge-shaped scale 

 occurs, the " cuneate " (see fig. 16 B). Sometimes a second or even a 

 third similar scale borders the lower lip. This scale may easily be over- 

 looked, lying partly or wholly concealed, as it may do, by the over- 

 lapping of the upper lip, so that the mouth should be opened when 

 looking for it. It occurs in no other land snake. 1 have never even 

 observed it in the hamadryad, but it is seen in a few species of sea-snakes. 

 A head is rarely so broken that one or other of these points cannot 

 be made out on one side. If, however, the head is mutilated beyond 

 recognition there is one feature about the scales over the back of a cobra 

 which is peculiar to itself. It is the concavity in the arms of the bracket- 

 shaped pattern which these form, and which I have shown by thickened 

 lines in fig. 17. Beside this, I have placed another drawing to 

 illustrate what is seen in other snakes, the pattern forming a chevron. 



"' This is a very easy point to determine if it is remembered that the shields immediately 

 behind the rostral (in land cuhibrinee) are called internssals, and the shields touching the 

 eye in front the praeoculars. In the iiistarces where the praefrontal shield touches the eye as 

 in Fig, IS), it is obvious that this shield from its size and position has a prior claim to be 

 considered a praefrontal, and in such a caee the prseocular is said to be absent. 



