132 DIVISION I. VERTEBRAL ANIMALS.—CLASS III. REPTILIA. 
his master having found, hard by, a banana tree, he applied its juice, mixed 
with treacle, to the wound, which recovered the dog, and quickly healed his 
sores. 
In India there is nothing so common as dancing Serpents, which are car- 
ried about in a broad, flat vessel somewhat resembling a sieve. These erect 
and put themselves in motion at the word cf command. When their keeper 
sings a slow tune, they seem, by their heads, to keep time; when he sings 
a quicker measure, they appear to move more brisk and lively. All animals 
have a certain degree of docility ; and we find that Serpents themselves can 
be brought to move and approach at the voice of their master. From this 
trick, successfully practised before the ignorant, it is most probable has 
arisen all the boasted pretensions which some have made to the charming of 
Serpents — an art to which the native Americans pretend at this very day. 
As a general thing, the non-venomous Serpents have the branches of the 
upper jaw furnished throughout their length, like those of the lower jaw and 
the palate, with fixed and solid teeth. There are three or four sub-equal 
ranges of these teeth in the upper part of the mouth, and two in the lower. 
On the contrary, the venomous Serpents are furnished with movable fangs. 
Tt should be remembered, however, that some snakes with solid tecth are 
exceedingly poisonous, especially those that have very large, black molars. 
Genus Boa. — The Boas. These are the largest of all serpents, attain- 
ing a leneth of from thirty to forty feet. They have a hook on each side 
of the anus, a compressed body, large towards the middle, small scales on 
the hinder part of the head, and a prehensile tail. They are capable of 
swallowing very large animals, even cattle, after having crushed them within 
their folds, and lubricated, with their saliva, as we have already described in 
our general remarks upon serpents. To enable them to perform such an 
extraordinary feet of deglutition, they have, at the extremity of the great 
Jung, —one lung is but half the length of the other, —a large air-bag, 
which contains the air requisite for respiration when the nostrils are closed 
in the process of swallowing. 
There are several species, which are distinguished by the difference in the 
teguments of the head and jaws. The Anaconda of South America does 
not differ materially from the Boa of Africa and India. They are all pow- 
erful animals, and justly objects of terror to the inhabitants of those coun- 
tries which are infested by them. 
All along the swampy banks of the Rivers Niger and Oroonoko, where 
the sun is hot, the forests thick, and the men but few, the serpents cling 
among the branches of the trees in infinite numbers, and carry on an un- 
ceasing war against all other animals in their vicinity. Travellers have 
assured us that they have often seen large snakes twining around the trunk 
