384 ZOOLOGY 



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. Apoda. — Degenerate Amphibia with neither legs nor tail; body 

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

 scales are imbedded in the skin. Represented by the, so-called blind-worms of 

 tropical countries. 



Order ll. Caudata. — Amphibia with tails persistent throughout' life; body 

 elongated; usually two pairs of appendages Csometimes only the anterior are 

 present), which may be poorly developed. 



The principal suborders are: 



1. Proteida, three pairs of gills; two pairs of gill openings; eyelids absent. 

 (Examples: Necturus, Proteus, Typhlomolge.) 



2. Meantes, three pairs of gills; three pairs of gill openings; no eyelids; no hind 

 limbs. (Examples: Siren, Pseudobranchus.) 



3. Mutabilia, no gills in adult; gill openings usually absent; eyelids commonly 

 present. (Examples: Cryptobranchus, Amblystoma, Diemyctylus, Plethedon, Am- 

 phiuma.) 



Order III. Salientia. — Amphibia in which the tail is absent 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 larvas usually 

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

 of gills lost in the adult. The Salientia embrace the Bufonidae or common toads, 

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

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



