64 



CAUDAL VERTEBRA. 



[chap. 



neural arch diminishes and finally disappears, leaving for a 

 while a pair of processes at each extremity of the vertebra, 

 the remains of the parts of the arch which bore the zygapo- 

 physes ; the transverse process is much reduced, and con- 

 fined to the posterior extremity of the body, a second one 

 appearing at the anterior extremity. Even these rudiments 

 of processes gradually cease to be perceptible, and nothing 

 is left but a cylindrical rod of bone, representing the centrum 

 alone of the vertebra. These diminish in size towards the 

 apex of the tail, the last being usually a mere rounded nodule. 



Fig. 27. — Anterior surface of twelfth Fig. 28. — Upper surface of twelfth caudal 

 caudal vertebra of Leopard, g. w vertebra of Leopard, §. m metapo- 

 metapophysis ; p processes serially physes ;;* processes serially continuous 

 continuous with those which support with those which support the posterior 

 the posterior zygapophyses in the an- zygapophyses in the anterior vertebrae, 

 terior vertebrae ; /: hypapophyses The t transverse process ; t' anterior trans- 

 process on the side of the body be- verse process, 

 tween w and h is the anterior trans- 

 verse process. 



Connected with the under-surface of the caudal vertebrae 

 of many animals which have the tail well developed, are 

 certain bones, formed more or less in the form of an in- 

 verted arch (Fig. 29), called chenron bones (French, Os en V ; 

 German, U?tierbogen ; hcE7?iapophyses, Owen). These are 

 always situated nearly opposite to an intervertebral space, and 

 are generally articulated both to the vertebra in front and the 



