AMPHIBIA 383 



larval organs disappear? What new organs are introduced? 

 Compare other amphibians as to the degree and facts of meta- 

 morphosis. 



410. Classification of Amphibia. 



Order I. Gymnophiona. Degenerate Amphibia with neither legs nor tail; 

 body worm-like; no gills nor gill-slits in the adult; eyes more or less degenerate. 

 Scales are present in the skin. Represented by the so-called blind-worms of 

 tropical countries. 



Order II. Urodela. Amphibia with tails persistent throughout life; body 

 elongated; usually two pairs of appendages (sometimes only the anterior are 

 present), which may be poorly developed. 



The principal suborders are: 



1. Perennibranchiata, in which the gills persist throughout life (Necturus or 

 water-dog, Siren or mud-eel, and certain blind forms found in caves). 



2. Derotremata, losing the gills in the adult but retaining a spiracular opening; 

 in the side of the neck which represents the gill-slit. (Examples: " Congo-snake '* 

 of the gulf states, giant salamander of Japan.) 



3. Myctodera, which lose all traces of water-breathing. (Examples: Newts, 

 salamanders, etc.) 



Order III. Anura. Amphibia in which the tail is absorbed in the adult 

 condition, if present in the embryo. Two pairs of appendages, the posterior of 

 which are well developed. Undergo a metamorphosis in which the larvse usually 

 have the "tadpole" form, with gills and tail but without appendages. All traces 

 of gills lost in the adult. The Anura embrace the Bufonidas or common toads, 

 the Ranidae or common frogs, the Hylidae or tree-toads, and other less common, 

 families. The Anura include the great majority of the species of Amphibia. 



