VIPERS AND Pil WiPiks 
gland to the wound which their sharp end has made 
in some hostile or edible creature. The reduction of 
the poison fangs and their tubular, not merely grooved, 
structure is a mark of the viperine dentition. More- 
over, this particular viper has a little pit on the side 
of the face, as has the rattlesnake, from which char- 
acter it is known as a pit viper, a distinction from the 
common viper of this country and its allies, which are 
perfect as vipers, but have no pit. This snake haunts 
the leafy branches of trees, and, as we suppose, in 
accordance with that habit, its uniform hue hides it 
when motionless. This same shade of green is not 
uncommon among reptiles. It is to be seen, for ex- 
ample, in the European green lizard, and in a very 
beautiful gecko from Madagascar, which has the name 
of Phelsuma madagascariensis, in various chameleons, 
and in other forms. The green is of the same timbre 
in all of them. This little viper is therefore doubly 
armed to hold its own. It can escape observation by 
its harmonious colouring, harmonious, that is to say, 
with leafy or grassy surroundings, and it can give a 
thoroughly good account of itself if detected. 
ORDER CHELONIA 
The tortoises and turtles form an assemblage about 
the limits of which there can be no possible mistake. 
They are encased more or less completely in a bony 
box, which is generally overlaid by epidermic scales, 
quite comparable with those of lizards. The bony box 
is produced by ossifications within the skin, and has, 
of course, nothing to do with the skeleton proper, 
although its bones are often fused with bones of the 
true skeleton. The Chelonia also have toothless jaws, 
the want of teeth being to some extent compensated 
by the existence of a horny sheath to the jaws, which 
is exactly comparable to the bird’s beak. 
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