42 
01^ THE PHYSIOGNOMY OF SEEPENTS. 
to detain their prey^ and to assist deglutition. Inde- 
pendently of these functions, the teeth often conduct into 
the wounds, which they make a liquor, secreted by glands 
lodged in the head. These glands are of two kinds : the 
one, like the salivary glands of mammals and birds, is 
composed of numerous small grains, which secrete a fluid 
similar to saliva, intended to prepare nutritious substances 
for digestion ; the others have a different structure : they 
form a thick sac, the interior of which is divided into 
numerous compartments : they distil a liquor which, 
by the deadly effects it can produce in the animal body, 
becomes the fatal implement, by means of which ser- 
pents kill the animals which serve for their support. The 
salivary glands are the property of all Ophidians ; but 
scarcely a fourth part of the known species are also pro- 
vided with the poison glands. The teeth, which conduct 
the poison into the wounds, are always hollow, and, per- 
forated at both ends, are called fangs : these are al- 
ways placed at the anterior end of the maxillary bone, 
where they are fixed, and often are its only occupants : 
concealed in the gums, which here form a sort of sheath, 
they are recumbent, while the snake is in a state of re- 
pose, but are elevated when he intends to bite. The rest 
of the teeth, and all those of non-venomous serpents, are 
solid, with the exception of the cavity that contains the nu- 
tritive organs of the tooth. It is observed, however, that 
a considerable number of non-venomous serpents of differ- 
ent genera have jaws provided with one or two teeth 
larger than the rest, and generally grooved by a canal, ex- 
tending along their anterior face. These channelled teeth 
always are found at the posterior part of the maxiUary 
bone ; and we but rarely find a second iii the middle of 
the jaws : they have no other function than pouring into 
the wounds they make a more copious saliva, secreted by 
the posterior salivary glands, which are most voluminous 
in the region occupied by those channelled teeth.^ 
* It is erroneous to class with venomous serpents those snakes which 
have long and channelled jpostmor teeth. Vague and contradictory ac- 
counts of the qualities of Ophidians, furnished by the natives of Java, 
have probably caused this mistake. In the Indies^ as in Brazil, in 
