136 



AMPHIBIA 



CLASS II 



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



J and also on the 



imx ^"Ntt 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 

 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 - Avater in- 

 habitants, or live 

 in damp shady 



,'eii. A, Dorsal: and B, Palatal places OU the 

 , Maxilla; Na, Nasal; Prf, Pre- t -, ^ • .- 



- - - ' -' - i""-i subsisting 

 on worms, gas- 

 tropods, small 



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

 deposits, and are always very rai'e. But one Mesozoic skeleton is known, and 

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



Fig. 229. 



Skull of Cryptohranchns jajioninis, v. d. Hoev 

 aspects. C, Lower jaw. Pmx, Premaxilla ; Mx, juaxnia , j<u, i-«Ltsiii, j-,j, jric- ■■ ■< 

 frontal ; Fr, Frontal ; I'a, Parietal ; OSph, Orbitosphenoid ; ErO, Exoccipital ; Qn, land 

 Quadrate ; S(j, Squamosal ; Pt, Pterygoid ; PSpli, Parasphenoid ; Vo, Vomer ; G, 

 Palatine vacuity ; N, External nares. 



Sub-Order A. ICHTHYOIDEA. 



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

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

 small, without distinct lids. Acpiatic habitat. 



