136 



AMPHIBIA 



CLASS II 



Small, acutely conical pleurodont teeth (Fig. 229) are present in both jaws, 



^ and also on the 



Tmx ^"^au vomer and pala- 



tines. 



The peäoral 

 arch remains for 

 the most part car- 

 tilaginous. Only 

 the ventral por- 

 tion of the sca- 

 pula, together 

 withthe proximal 

 ends of the cora- 

 coid and precora- 

 coid unite to form 

 a common osseous 

 plate. In the 

 pelvic arch only 

 the ilium and 

 large ischia are 

 regularly ossified, 

 the pubis remain- 

 ing, as a rule, car- 

 tilaginous. The 

 limbs do not difFer 

 essentially from 

 those of Stego- 

 cephalians, and 

 the carpus and 

 tarsus exhibit 

 various degrees 

 of ossification. 



Urodeles are 



fresh - water in- 



habitants, or live 



Fig. 229. in damp shady 



Skull of Cryptobranchus japonicus, v. d. Hoeveii. ^.Dorsal; and B, Palatal places On thc 



aspects. C, Lower jaw. Pmx, Preinaxilla ; Mx, Maxilla ; Na, Is'^asal ; Prf, Pre- -i -, i • +• 



frontal; Fr, Frontal; Pa, Parietal; OSph, Orbitosphenoid ; ExO, Exoccipital ; Qxi, lanü, SUDSlStmg 



Quadrate; Sq, Squamosal ; Pt, Pterygoid ; PSph, Parasphenoid ; Vo, Vomer; G, ^„ -wT-nT-me o-n« 



Palatinevacuityri^, Externalnares. ! ^" WOrms, gas- 



tropods, small 

 aquatic animals, and fish spawn. Fossil remains occur only in fresh-water 

 deposits, and are always very rare. But one Mesozoic skeleton is known, and 

 the few Tertiary genera are scarcely distinguishable from those now living. 



Sub-Order A. ICHTHYOIDEA. 



Vertebrae amphicoelous, with persistent remnants of notochord. Three pairs of 

 external gills, or in their absence a persistent branchial apert'ure. 

 small, without distinct lids. Aquatic habitat. 



