ORDER BATRACHIA. 389 



this trunck or immediately from the veins which 

 form it, that the greatest part of the arterieg which 

 nourish the body spring, and even those which con- 

 duct the blood to be respired in the lungs. 



But in the species which lose their gills, the 

 branches which repaired thither become obliterated, 

 excepting two, which are united in a dorsal artery, 

 and each of which sends a small branch to the lungs. 

 This is the circulation of a fish, metamorphosed 

 into the circulation of a reptile. 



The batracians have neither scales nor carapace, 

 a naked skin covers their bodies.* With the excep- 

 tion of a single genus, they are without claws to 

 the toes. 



The envelope of their eggs is simply membranous. 

 The male disposes the female to lay them, by very 

 long embracings, and in many species they are not 

 fecundated but at the moment of their coming 

 forth. 



These eggs swell greatly in the water after having 

 been laid. The young does not differ from the 

 adult merely by having gills. Its feet are developed 

 only by degrees, and in many species there are a 

 beak and tail which are to be lost, and intestines 

 of a different form from those of the adult j some 

 species are viviparous. 



* M. Schneider has proved that the scaly frog of Walbaum appeared 

 such only by accident, some scales of lizards, which were kept in the same 

 vessel, having attached themselves to its back. 



