ANATOMY OF VERTEBRATES. 



49 



Gl 



f" 



genus called Pleurodeles. In the land Salamander the backbone 

 is strengthened by the ball-and-socket articulation of the trunk- 

 vertebrae. Cuvier notices a curious inconstancy in the place of 

 attachment of the pelvic arch, sometimes to the fifteenth,, some- 

 times to the sixteenth, 

 and in one instance sus- 

 pended by the right pier 

 to the sixteenth, by the 

 left to the seventeenth, 

 vertebra, in Salaman- 

 dra atra. 1 



The ophiomorphous 

 batrachia are remark- 

 able for the multiplicity, 

 the theriomorphous for 

 the paucity, of distinct 

 vertebra? in the trunk ; 

 these latter have the 

 ball-and-socket articula- 

 tion. The frog, fig. 44, 

 A, has nine vertebrae 

 and the coccygeal style 

 c ; but by coalescence of 

 this with the sacrum, 

 and of the atlas with the 

 second vertebra, in the 

 Surinam toad (Pipa), the 

 number of distinct trunk- 

 segments is in that 

 species reduced to seven. 



In Rana boans the 

 atlas has no diapophy- 

 ses ; but they are present 

 and of great length in 

 the succeeding vertebrae 

 to the sacrum inclusive, where they are thick and support by 

 their truncate ends two long rib-like bones, ib. A, 62, which 

 expand at their distal ends, and unite there to two partially 

 anchylosed bony plates, 64, which complete the haemal arch of the 

 ninth segment of the trunk. The superior developement of this 

 arch relates to the great size and strength of its appendages 



1 CLI. torn. v. pt. ii. p. 413, 

 E 



SC' 



TVii 



Skeleton of frog, A ; vertebra B and carpus c of toad. 



