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ZOOLOGY. 
such species are only preserved from extinction by their 
nocturnal habits and their protective resemblance to the 
herbage and leaves of trees, there is a little bright red and 
blue frog in Nicaragua which hops about in bright day- 
light. It owes its life to its bad taste, for ducks and fowl 
will on this account not eat it. 
Class VI. — Eeptilia {Lizards, Snahes, Turtles, and 
Crocodiles), 
General Characters of Reptiles. — While the fishes and 
Amphibians are much alike, the reptiles, with their scales 
and claws, come near the birds. In their skull and skeleton, 
and in the 4-chambered heart of the crocodiles, they are also 
bird-like. Eeptiles, then, are characterized by having their 
bodies covered with scales and their toes ending in claws, 
with the exception of the snakes, which have no legs and 
consequently no claws. The reptiles also, unlike the fore- 
going vertebrates, have true nostrils like those of birds and 
beasts, and there is in all except snakes an upper and a 
lower movable eyelid, while the tongue is long and forked 
and can be darted out after insects. They have also true 
lips, and a long windpipe like that of birds. There are 
3000 species of living reptiles known, of which 358 are 
North American. 
Orders of Reptiles. 
1. Body long, slender, cylindrical, limb- 
less Ophidia (Snakes). 
2. Body with a long tail; usually two 
pairs of limbs ..Lacertilia (Lizards), 
3. Body enclosed in a thick shell Chelonia (Turtles). 
4. Lizard-like; vertebrae hollow at each 
end miyncliocephalia (Sphenodon). 
5. Body thick-scaled; teeth in sockets. Crocodilia (Crocodiles). 
Order 1. Opliidia (Snakes). — Notwithstanding the fact 
that snakes have no legs, they can creep, glide, grasp, sus- 
pend themselves, erect themselves, leap, dart, bound, swim, 
