//. TYPES IN DETAIL IVITH THEIR SUBORDINATE GROUPS. 41 



nal, present at some stage, gen- 

 erally transitory. Lungs usually 

 present, with larynx and trachea. 

 Paired limbs of the hand-form 

 (cheiropterygium) with normally 

 five digits, often reduced in 

 number. Two occipital con- 

 dyles. 



Order i. Urodela Body elongated. Tail persistent. 



In some of the lower members of 

 the group one or two gill-slits per- 

 sist throughout life, and in a few, 

 the external branchiae also persist. 

 Typically lungs are present in the 

 form of simple, attenuated sacs, 

 but in some cases they are wanting 

 and are functionally replaced by 

 a secondary respiratory organ 

 formed by the walls of oesophagus 

 and pharynx and worked by 

 muscles. 



X Necturus, Desmognathus. 



Order 2. Gymnophiona Serpentine subterranean forms 



without tail, limbs or gills. In- 

 tegument with minute scales 

 sunken in pits. 



X Qzcilia. 



Order 3. Anura Compact, cephalized forms, with 



tail present in larval life only. 

 Hind legs enormously developed 

 and used for leaping and swim- 

 ming. No gills when adult. 



X Rana, Bufo, Hyla, Pipa. 



B. AMNIOTA Embryo enveloped in an amnion; 



breathe by lungs and never by gills; 

 mainly terrestrial. 



Super-class II. SAUROPSIDA Skin thin and dry, covered with a 



