GENERAL CLASSIFICATION OF POISONOUS SNAKES 
9 
prey, but in order to deal it a mortal blow by injecting the venom 
into its flesh. 
In the normal position they lie almost 
horizontally, and exhibit no mobility of their 
own. But, when the animal prepares to 
bite, their erection is effected by the snake 
throwing its jaw back; and this movement, 
which is always very sudden, enables it at 
the same time to compress its poison- 
glands, by the aid of special constrictor 
muscles. 
On examining the various species of 
poisonous snakes, we observe very sharply 
marked differences in the arrangement and 
Thus, in the 
long, extraordinarily 
dimensions of the teeth. 
VIPERIDÆ they are 
sharp, and capable of producing deep wounds 
(fig. 2, a, and fig. 3). 
by an almost completely closed canal, from 
the base, 
They are traversed 
which communicates with the 
poison-duct, to the neighbourhood of the 
point, where it opens very obliquely on the 
convex surface (fig. 3, A and D). 
In the Ælapinæe sub-family of the Colu- 
bride, and especially in the Hydrophiine, 
the teeth are much shorter and simply 
grooved or canaliculate ; that is to say, the 
canal with the 
throughout its extent by a narrow slit, 
communicates exterior 
which traverses the entire convex surface 
of the tooth (figs. 4, 5, and 6). 
It does not follow from this that the 
the bites of these reptiles are less dangerous; 
E 
Fic. 4.—B, Fang of one 
of the Colubrida (Naja 
tripudians) ; B, transverse 
section. 
Fic. 5.—c, Fang of one 
of the Hydrophiine (Hydr- 
ophis pelamis); F, transverse 
section. 
Fic. 6.—Three transverse 
sections of a poison-fang 
of one of the Colubride, 
through AA, BB, CC; PP, 
pulp cavity ; V V v, poison- 
canal (groove). (After C. J. 
Martin.) 
