GENERAL CLASSIFICATION OF POISONOUS SNAKES 11 
They are oval in shape, and may, in Naja tripudians for example, 
attain the size of a large almond (fig. 8). 
Their structure is the same as that of the salivary glands of the 
larger animals. The poison that they secrete accumulates in their 
acini and in the efferent duct that opens at the base of the corre- 
sponding fang. 
Each gland is surrounded by a capsule, to which are partly 
attached the fibres of the masseter muscle, which violently com- 
presses it and drives 
the poison, just as 
the piston. of a 
syringe would do, in- 
to the canalicule or 
groove of the fang. 
In a few venom- 
ous snakes the gland 
is developed to such 
an extent that 1t ex- Hi. 8.—Porson-ananp AND FANGS or a Venomous: 
tends as far as the SNAKE (Naja tripudians, Colubridæ). (Natural size.) 
first ribs r, Lobe of the gland ; D, poison-duct ; F, fang attached 
4 to the maxillary bone; GG, gland; M, capsule of mucous 
re species, ON membrane surrounding the fangs; R, reserve fangs; 
the contrary, that 44, muscular fascia covering the gland. 
Haven “tlie poison- (After Sir Joseph Fayrer.) 
teeth placed in the 
hinder part of the mouth (Opisthoglypha) have glands but little 
P D CUIR 5 
developed. 
Muscular Apparatus of the Head.—Figs. 9 and 10, 11 and 12 
show the arrangement of the principal muscles that work the jaws 
and glandular organs in Vipera russellii and Naja tripudians, which 
respectively represent the most formidable types of Viperidæ and 
venomous Colubride. 
‘It is not necessary to give a detailed description of each of these 
muscles. Let it suffice to point out that all contribute in giving 
_the greatest elasticity to the jaws, and at the same time strength 
