The British Guiana Museum. 269 
most interesting of the lizards is the chameleon, a form 
confined to the Old World ; the so-called colonial 
chameleon is quite a different form, though also able to 
change its coloration. 
Of the order Crocodilia> which includes the crocodiles 
and alligators, several forms of the latter are shewn. The 
differences between the crocodiles and alligators have 
already been pointed out. The former are chiefly found in 
the tropical parts of the Old World, though also occurring 
in tropical America; the latter are only found in the Ameri- 
can continent. The peculiar armature of the skin of the 
Crocodilia is one of the chief marks of the order, but this 
never forms a box as in the Chelonia. Beneath the outer 
horny epidermis is present a layer of hard bony plates 
along the elongated lizard-like body ; the tongue, more- 
over, is never free from the floor of the mouth. They are 
all oviparous. 
Of the order Ophidia or snakes, a few by no means 
satisfaftory skins are shown. The long worm-like body, 
the covering of scales, the absence of limbs, the absence 
of an eye-lid, and the unfused condition of the lower jaw 
in front, are marks easily noticed about these animals. 
The ball and socket arrangement of the joints of the 
back-bone, the large number of ribk which are functional 
legs in snakes, and the quadrate bone between the 
upper and lower jaw, have already been alluded to, in the 
notice of the skeleton of the yellow-tail. From the fa6l 
that the two parts of the lower jaw are only conne6led 
by ligaments with each other in front, and behind 
with the quadrate bone, which again is connected by 
ligaments with a movable bone (Squamosal) of the 
upper part of the head, it will be readily understood how 
MM 
