136 



AMPHIBIA 



CLASS II 



A 



DPmx 



1* 



Mx 



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



and also on the 

 vomer and pala- 

 tines. 



The pectoral 

 arch remains for 

 the most part car- 

 tilaginous. Only 

 the ventral por- 

 tion of the sca- 

 pula, together 

 with the proximal 

 ends of the cora- 

 coid and precora- 

 coid unite to form 

 a common osseous 

 plate. In the 

 pelvic arch only 

 the ilium and 



I'mx: 



and 



St 



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 

 in damp shady 



Skull of Cryptdbranchus japonicus, v. d. Hoeven. A, Dorsal; and B, Palatal places Oil the 



aspects. C, Lower jaw. Pmx, Premaxilla ; Mx, Maxilla; Na, Nasal; Prf, Pre- -■ -, -■ • ,- 



frontal; Fr, Frontal; Pa, Parietal; OSph, Orbitosphenoid ; ExO, Exoccipital ; Qu, land, SUDSlStmg 



Quadrate; Sq, Squamosal; Pt, Pterygoid; PSph, Parasphenoid ; Vo, Vomer; G, nri .„„,,,,,„ -„& 



Palatine vacuity ; N, External nares. ' U11 vvuiuift, & <t&- 



tropods, small 

 acpiatic 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. 



«irt-~ 



large ischia are 



Fig. 22'.'. 



Sub-Order A. ICHTHYOIDEA. 



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

 perennial external gills, or in their absence a persistent branchial aperture. Eyes 

 small, without distinct lids. Aquatic habitat. 



