ANATOMY or VERTEBRATES. 



45 



and along the whole liEcmal region of the tnmk, from the head to 

 the tail. This want of correspondence with the number of the 

 true segments of the endoskeleton, and the seat of developement 

 of the inter- and dermo-neurals and inter- and dermo-hasmals, with 

 some minor considerations, led me, in 1845, to substitute for the 

 views and illustration of the typical vertebra; pro23osed by Geoffroy 

 St.-Hilairc, ' and then accepted and taught by Professor li. E. 

 Grant - in this country and by others abroad, the interpretation of 

 the supposed type-exemplar, which is contrasted with Geoftroy's in 

 fig. 40. The names applied by the French philosophical anatomist 

 to the several parts of the combined endo- and exo-skelctal segment 



Plciu-oncctcs Solca. XLIII. 



are opposite the left hand of the reader : those applied to them 

 in my ' Archetype of the Skeleton ' are opposite the right hand. 



The small exogenous process standing out from the sides 

 of the centrum is a dismemberment of the parapojDhysis ; in 

 the first caudal vertebra it is given off' from the base of the 

 parapophysis, increases in length in the second caudal, rises upon 

 the side of the centrum in the third, and becomes distinct from 

 the parapophysis in the fourth : it diminishes and disajjpears in 

 the ninth and tenth caudal verteljric. In Polijptems and ]\Iura3- 

 noids a transverse process coexists, from the same cause, with the 

 parapophysis. This, in the twenty-fifth trunk-vertebra of 

 Murcena Helena,'^ bifurcates, and in the following vertebra} the 



' Memoires du Mus. 4to, ix. 1822, p. 119, pi. y. 

 ' Lectures on Conip. Anat. p. 58. ' xnv. p. 14. 



No. 37. 



