124 



PALEONTOLOGY 



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soft "notochord" (c), which 

 has been dissolved away. 

 The cylindrical gelatinous 

 body, so called (in Latin 

 chorda dor sails) pre-exists to 

 the formation of the bony 

 bodies of the vertebra? in all 

 vertebrate animals ; and the 

 development of those bodies 

 seems never to have gone 

 beyond this embryonal phase 

 in any palaeozoic fish ; such 

 fishes are accordingly termed 



jt " notochordal," as retaining 



g the notochord. 



"% There are but two genera 

 $ ^ of existing fishes which 

 •Jf # manifest, when full grown, 



o_ such a structure, associated 

 with ossified peripheral ele- 

 ments of the vertebra? — viz., 

 the Protopterus of certain 

 rivers of Africa,* and the 

 Lepldoslren of certain rivers 

 of South America. Those 

 fishes alone would, if fossi- 

 lized, present the appearance 

 of the vertebral column 

 shown in fig. 45, and which 

 characterizes all the oolitic 

 fossil ganoid fishes (see figs. 



* Sec Linnaaan Transactions, vol. 

 xviii. ; ami Proceedings of the Lin- 

 naaan Society, April 2, 1839. 





