NATURE OF LIMBS, 



65 



orbital, and supratemporal scale-bones are removed, to- 

 gether with the opercular bones, from the head ; and the 

 inter neural and dermoneural spines, with the interha3mal 

 and dermohsemal spines, are removed from the trunk. 

 The endoskeleton is also reduced to a very simple condi- 

 tion ; the advance characteristic of the higher class being 

 appreciable only by a comparison of it with the skeleton 

 of the most batrachoid of fishes — e. g. the protopterus 

 (No. 380). 



We then perceive that the bodies of the vertebrae, in 

 the true batrachian, are distinctly ossified, though pre- 

 serving, in the perennibranchiate species, a deep, conical, 

 jelly-filled cavity both before and behind (Cut 11), C ; they 



SACRAL VERTEBRA AND CONTIGUOUS VERTEBRAE — MENOPOME. 



have also coalesced with the neural arches, as these have 

 with their spines, which are, however, scarcely prominent, 

 except in the tail. The transverse processes are developed 

 not only from the centrum but from the base of the neural 

 arch, and are formed by both parapophyses and diapo- 

 physes ; and they coexist with distinct haemapophyses in 

 the tail (z6.), H. With these, likewise, coexist cartilagin- 

 ous pleurapophyses (Z^.), pl^ in the second, third, and 



