26 
GUIDE BOOK TO THE BRITISH MUSEUM. 
together on the sides, but when it leaps from branch to branch they are 
spread out and act as a parachute ; the frilled agama ( Chlamydosaurus\ 
which has a large folded frill round its neck like a queen Elizabeth’s 
ruff, which it can elevate when excited. The lower shelves contain 
the different kinds of chameleons, which are found in Africa and 
India, and the islands near them ; they have been long celebrated on 
account of the rapidity with which they change their colours; and 
they are remarkable for the distance to which they can protrude the 
tongue in order to catch insects, which form their principal food. 
Cases 8—19. The Snakes or Serpents. 
They differ from the lizard in always swallowing their food entire. 
Case 8. The Poisonous Serpents. 
In the upper shelves are placed the Rattle-snakes peculiar to 
America, which have a rattle at the end of the tail ; this rattle is formed 
of a series of horny joints, fitting one into the other, which the animal 
can shake at pleasure ; there are several detached rattles, to shew their 
structure ; the fer de lance of the French colonists in South America, 
and the different kinds of poisonous snakes allied to the rattle-snake 
which come from India. The lower shelves contain the Vipers ; as 
the adders of Europe, the long-nosed viper ( Ammodytes ) of Southern 
Europe ; the crested or double-horned viper of Egypt and North 
Africa; the nosehorn viper of Guinea, and the puff adder or short- 
tailed viper of the Cape of Good Hope and Western Africa. The 
viper is the only reptile found in Great Britain possessed of dangerous 
poisonous, qualities. 
Cases 9—19. The Harmless Snakes. 
Cases 9 — 17. The genera allied to Coluber; as the water snakes 
( Tropidonotus ) and the common ring snake of England ; the coral snake 
( Elaps ), which is marked with alternate black and red rings; the flat- 
tailed coral snake, which lives in the sea and has a flattened tail ; the 
juggler snakes ( Naja ), which have the faculty of dilating the skin of the 
neck so as to form a kind of hood over the head; they are found in 
Africa and India, and are used by the native jugglers in their exhibi- 
tions ; the Indian species have usually a yellow spot on the back of the 
neck, somewhat resembling a pair of spectacles. These snakes have 
their hinder teeth larger than the rest ; are furnished with a poison tube, 
like the fang of the rattle-snake and vipers. The tree snakes, or coach- 
whip snakes have very long bodies ; they live chiefly on frees ; one of 
these is peculiar for its nose being much produced. 
Case 18. The genera allied to the Boa ; they are the only snakes 
furnished with the rudiments of legs; they are not venomous, and kill 
their prey by crushing it between the folds of the body, generally at the 
same time twisting the end of their prehensile tail round a tree or some 
other fixed point, in order to increase their power; some come from 
America, some from India, and a few from Africa. 
Case 19. The Sea Snakes, which are peculiar to the seas of Asia 
and New Holland, and are in some degree dangerous, as many of the 
species have small fangs dispersed amongst the true teeth ; some of 
them grow to a very large size ; they sleep on the shores coiled up, and 
are sometimes found asleep on the surface of the calm tropical seas. 
