FROGS. TREE-FROGS. 71 



is generally soft, and, contrary to what we see in most mammals, 

 it is fixed to the edge of the jaw only by its anterior extremity, 

 so that it can be folded backwards, or turned out of the mouth. 

 Finally, the skeleton of these reptiles (Fig. 29, Page 58.) is entirely 

 unprovided with ribs, and the inspiration of air can be effected only 

 by a movement analogous to that of deglutition, in which the 

 animal dilates the 'throat to fill it with air ; then, closing the poste- 

 rior nostrils with the tongue, contracts the muscles of the swallow, 

 and forces this fluid to enter the lungs: to throw one of these 

 animals into a state of asphyxia, it is only necessary to keep the 

 mouth open for a certain time. 



10. The FROGS, flana, have the body more tapering than 

 the other Anoura; the hind feet are very long, very strong, and 

 more or less palmate, which enables them to swim and leap well. 

 The skin is smooth, and the males have on each side of the neck, 

 beneath the ears, a thin membrane which becomes inflated, when 

 they croak. They are distinguishable from toads by a row of 

 very fine, small teeth, all around the upper jaw. These reptiles 

 ordinarily keep on the banks of ponds and rivulets, and precipi- 

 tate themselves into the water on the slightest danger : they feed 

 only on living prey, and eat the larva of aquatic insects, worms, 

 small mollusks, and flies. In winter they bury themselves in the 

 mud, or in holes, and do not eat. 



1 1 . We give the name of TREE-FROGS, Hyla, to Batrachians 

 which do not differ much from frogs, except that the extremity of 

 each one of the toes is enlarged, and rounded into a sort of viscous 

 pellet or ball, (/%. 36.) that p . 



enables them to adhere to 

 bodies upon which they 

 climb, and to ascend trees. 

 Endowed with great sup- 

 pleness and agility, Tree- 

 frogs travel very lightly 

 on the most flexible bran- 

 ches. During the whole 

 summer they live, in this 

 manner, on trees, pursuing 

 insects ; but in winter they 

 retire to the bottom of the COMMON TREE-FROG. 



water like frogs, and do not return again to the humid woods in 

 the spring, till after they have deposited their eggs. The common 



10. What are the -general characters of Frogs? How are they distin- 

 guished from Toads ? What are the habits of Frogs ? 



11. What are Tree-Frogs ? What are their habits ? 



