CLASSIFICATION 



647 



Sub-Class II. Lissamphibia. (About 1,000 species, nearly 900 of which 

 are frogs and toads. Figs. 315, 376). 



Order I. Apoda (Gymnophiona) Limbless Amphibia. (Fig. 373). 



These are also called caecilians and sometimes "blind-worms." They 

 are without limbs or limb-girdles. They burrow in the earth and are 

 found in warm climes. The cranium is like that of the reptile in out- 

 ward appearance but the bones which constitute it are the same as those 

 which go to form any amphibian cranium. The skin is smooth and 

 slimy with many ring-like folds. There are as many as 200 to 300 

 vertebrae in some species. The eyes are rudimentary and probably 

 functionless. There is a feeling-organ protruded from between eye and 

 nose which serves to guide the animal. Some are oviparous, while 

 others are viviparous. 



Fig. 373. Apoda. 



Ichthyophis glutinosa. 1, nearly ripe embryo, with gills tail-fin, and with 

 considerable amount of yolk ; 2, a female guarding her eggs, coiled up in an under- 

 ground hole ; 3, a group of newly laid eggs ; 4, a single egg, enlarged and 

 schematised to show the twisted albuminous strings or chalazae inside the outer 

 membrane, which surrounds the white of the egg. 5, Caecilia, emerging from 

 burrow. (After P. and F. Sarasin.) 



Order II. Urodela (Tailed Amphibia). (Figs. 315, 374). 



These are the mud-puppies (Necturus), salamanders, newts, and 

 efts. Many authors call all urodeles with adult external gills, Perenni- 

 branchiata, though the following grouping is the more common. 



Family I. Amphiumidae (Fig. 374). 



This family is without external gills in the adult stage. There are 

 only two genera, Cryptobranchus and Amphiuma (Fig. 374). 



Cryptobranchus allegheniensis (Fig. 374), is the well-known "hell- 

 bender" of our Eastern States. 



Cryptobranchus japonicus is the giant salamander of Japan. 



Amphiuma (Fig. 374) has only one species which ranges from Caro- 



