PHYSIOLOGY AND COMPARATIVE ANAT031Y. 641 



the Nose-vertebra, in his work On the Signification of the Bones of 

 the Skull, published in 1807 : and in various degrees, "with similar 

 views promulgated by Spix (1815), Bojanus (1818), Geoffroy (1824), 

 Carus 1828. And I believe that these views, bold and fanciful as they 

 at first appeared, have now been accepted by most of the principal 

 physiologists of our time. 



But another aspect of this generalization has been propounded amonor 

 physiologists ; and has, like the others, been extended, systematized, 

 and provided with a convenient language by Mr. Owen. Since animal 

 skeletons are thus made up of vertebra, and their parts are to be under- 

 stood as developements of the parts of vertebrae, Geoffroy (1822), 

 Carus (1828), Miiller (1834), Cuvier (1835), had employed certain 

 terms while speaking of such developements ; Mr. Owen in the Geolo- 

 gical Transactions in 1838, while discussing the osteology of certain 

 fossil Saurians, used terms of this kind, which are more systematic 

 than those of his predecessors, and to which he has given currency by 

 the quantity of valuable knowledge and thought which he has embo- 

 died in them. 



According to his Terminology, 3 a vertebra, in its typical completeness, 

 consists of a central part or centrum ; at the back of this, two plates 

 (the neural apophyses] and a third outward projecting piece (the neu- 

 ral spine), which three, with the centrum, form a canal for the spinal 

 marrow; at the front of the centrum two other plates (the hcemal 

 apophyses] and a projecting piece, forming a canal for a vascular trunk. 

 Further lateral elements (pleuro-apophyses) and other projections, are 

 in a certain sense dependent on these principal bones ; besides which 

 the vertebra may support diverging appendages. These parts of the 

 vertebra are fixed together, so that a vertebra is by some anatomists 

 described as a single bone ; but the parts now mentioned are usually 

 developed from distinct and independent centres, and are therefore 

 called by Mr. Owen " autogenous" elements. 



The General Homology of the vertebral skeleton is the reference of 

 all the parts of a skeleton to their true types in a series of vertebrae : 

 and thus, as special homology refers all the parts of skeletons to a 

 given type of skeleton, say that of Man, general homology refers all the 

 parts of every skeleton, say that of Man, to the parts of a series of Ver- 

 tebra?. And thus as Oken propounded his views of the Head as a 

 resolution of the Problem of the Signification of the Bones of the Head. 



* Archetype and Homologies of the Vertebrate Skeleton. 1848, p. 81. 

 VOL. II. 41. 



