64 



GUIDE TO KEPTILES AND AMPHIBIANS. 



Fig. 63. 



vertebras. There are four front toes. Owing to the absence of ribs, 

 Frogs, like other Amphibians, can only breathe by swallowing air. 



The order is divisible into three main groups, the first of which, 

 forming the section Firmisternia, includes the Typical Frogs, or 

 Ranidw (480-493), the Dendrodatidm (499-500), Engystomatidm 

 (494-498), and Dyscophidm (401, 402). All these are character- 

 ised by the presence of a tongue and by the union of the two 

 inferior bones of the shoulder-girdle, or coracoids, in the middle 

 line of the chest to form a firm bar. In the Ranidw the trans- 

 verse processes of the sacral vertebra form simple rods, and 

 there are typically teeth only in the upper jaw, although in 

 Giinther's Frog (Ceratooatrachus guentheri, 490) of the Solomon 

 Islands, these are developed in both jaws. The Dendrodatidce have 

 both jaws toothless. The Engystomatidm and Dyscophidm differ by 

 the expanded sacral transverse processes. In the former teeth are 

 lacking in both jaws, but in the latter they are developed in the 

 upper one, while in Genyophrys, which may represent a family, the 

 lower jaw is alone toothed. Some Ranidm, like Rhacophorus (491), 

 are arboreal and have adhesive toe-pads and webbed feet, but it is 

 untrue that they use the latter as a 

 parachute. Certain species deposit their 

 eggs enveloped in foam in mud or grass 

 on the banks of ponds. Many kinds of 

 Rana, like the Bull-Frog, have internal 

 or external dilated vocal sacs. All the 

 American Dendro ootid® live in trees. 



The largest representative of the 

 group is the huge Rana guppyi (483), 

 of the Solomon Islands ; of this Frog 

 both the mounted skin and the skeleton 

 are shown. Another well-known, al- 

 though much smaller, species of which 

 a specimen is exhibited is the Indian 

 Tiger-Frog, R. tigrina (487). The 

 , ;il Common Frog {R.temporariaMD, the 

 Frog (Leptodactylus penta- continental Edible Frog (R. esculenta, 

 dactylics) to show structure 485), and the American Bull-Frog 

 characteristic of the Toad ^ catesoiana, 488), are also shown in 

 S rou P- the case. 



The Toads (Bnfonidce, 413-420) may be regarded as the typical 

 representatives of the section Arcifera, which also includes the 

 families Discoylossidce (435-439), Pelolatida (440-442), HijMcb 



