rorsoNous and non-poisonous snakes. 97 



seen during life, it is sometimes a difficult matter, and this arises 

 through basing one's opinions upon the presence of a hood, or one of 

 the characteristic marks on the back of the hood (viz., the spectacle in 

 the binooellate variety, and the saturnine mark, i.e., a black ellipse 

 round an elliptical black spot, on the monocellate variety). 



Fallacies. — These creep in in many ways, (a) During life the hood 

 is seen in other snakes, viz.^ in the Hamadryad, Naia bungarus, and in 

 .' onie harmless snakes. Most of these, however, can only dilate the neck 

 to a moderate degree, but one in particular, Psevdoxenodon macropsy 

 according to Giinther, dilates its hood to such an extent as to simulate, 

 and consequently be mistaken for, the cobra, (h) When a cobra is 

 dead the hood collapses and the neck presents a contour similar to the 

 rest of the body, and when the stiffness of 7'igor mortis has set in, 

 it is difficult and often impossible to detect the hood at all. (c) The 

 loose skin on snakes permits the neck being drawn out with ease in a 

 lateral direction, and one may imagine a hood to exist where in reality 

 none is present, {d) With regard to the characteristic marks on the 

 back of the hood above referred to, though usually one or other is pre- 

 sent, it is not unusual to find specimens with absolutely no mark at all 

 and many with marks modified, and hence misleading. I have myself 

 had ocular proof of these last three fallacies, which were demonstrated 

 to me unwittingly by intelligent men who had been years in India. 

 The only reliable means of recognising a cobra will be seen by referring 

 to fig. 1, in which it will be noticed that the prse-ocular scale (Pr.) 

 touches the inter-nasal (I). Compare fig. 1 with figs. 2, 3, 4 and 5. 

 This little point will distinguish this snake from all other snakes but 

 one, viz.^ Xylophis perroteti, some specimens of which share thi? 

 peculiarity. In Xylophis, however, there is only one pair of chin 

 shields, in the cobra there are two (as in fig. 13). 

 Hamadryad— iVaza bungarus vel Ophiophagus elaps^ etc., etc. 



This in its younger days might be easily confused with the mono- 

 cellate variety of cobra, and the same fallacies mentioned under cobra are 

 equally applicable here. The only certain test lies, in the presence 

 behind the parietals, of a pair of hirge scales which are in contact 

 with one another (see Oc. fig. 8). In almost all snakes small scales 

 begin on the head immediately behind the parietals. One other snake 

 is peculiar in having large scales behind the parietals, viz.^ Xenopeitis 



IS 



