IDENTIFICATION OF SNAKES. 49 
In some experiments which I conducted with a view of ascer- 
taining if certain species of snakes were immune to Puff Adder 
venom, I allowed the adder to bite them, either in the neck or 
somewhere about the abdomen. In nearly all cases the bitten 
snakes died a week or so later. However, I subsequently dis- 
covered that the deaths were caused not by the venom, but by 
the actual mechanical injury caused to the internal parts of the 
bitten snakes, by the large fangs of the Puff Adders. 
IDENTIFICATION OF SNAKES. 
In the identification of the species of snakes the colouration 
is a most uncertain guide. The systematic Zoologist examines 
the dentition to ascertain to what division the 
specimen belongs. There are three main divisions, 
viz. the AGLYPHA, or solid-toothed non-veno- 
mous snakes ; the OPISTHOGLYPHA, or hind- 
fanged, more or less poisonous snakes ; and the 
PROTEROGLYPHA, or front-fanged, typically 
venomous snakes. 
After finding out what family, sub-family, and 
genus the specimen is a member by means of 
the general formation of the body, scales, and 
shields, the zoologist identifies the species by 
examining the shields on the head and abdomen. 
The number and shape of the head and abdominal 
shields differ in the various species of snakes. | 
Sometimes they merely slightly differ in a species. a aren are an 
In these cases we term it a sub-species, if the  Smei4e AN ox, 
tend from throat 
; 1 to vent. 
difference is observed to be constant. OE 
1 some snakes this 
If you compare the head shields of two apne 
different species of snakes, you will notice they covers the vent, 
. : % ‘ is divided. _ In 
differinshape. If the abdominal (ventral) shields _, othersitis entire. 
5 F , C. Sub-caudal. 
are counted they will differ in number. So also These ae 
: 3 some snakes al 
will those from the vent to the end of the tail in two rows ; in 
: others in a single 
(sub-caudals). In some species of snakes the shield row. 
(anal) over the vent is divided. Inothersitisentire. Soalso with 
the sub-caudals. In some snakes they are in one row, and in others 
they are in two rows. Their number also differ with the species. 
E 
