310 REPORT— 1846. 



pare," Cuvier says, " the supraoccipital to the spinous processes which in 

 certain animals originate by special points of ossification and remain for some 

 time distinct from the rest of the vertebra : nevertheless, there is already here 

 a great difference of structure and function*." With regard to the points in 

 which Cuvier is willing to admit an ' analogy ' between the occiput and the 

 atlas, he subjoins, agreeably with his idea of the law which governed such 

 correspondences, — " These resemblances might naturally be expected in the 

 part of the head placed at the extremity of the vertebral column, and the 

 functions of which are, in fact, analogous to those of vertebrae, since it gives 

 passage, like them, to the great neural axisf." 



With regard to the feature of resemblance (quelque rapport) which some 

 had seen between the mastoid process and a transverse process, Cuvier founds 

 his objection to its application to the vertebral character of the occipital 

 bone on a false homology. Concluding that the mastoid in man (fig. 2.5, s) 

 was homologous with the paroccipital in the hog (fig. 22, 4) J and some 

 other quadrupeds, he deems the determination of the paroccipital as the 

 transverse process of the occipital vertebra to be invalidated by the fact 

 that the ' mastoid ' belongs, in man, not to the occipital but to the petrosal. 

 There were cases, however, not unknown to the able Editors of the posthu- 

 mous edition of the ' Lecons d'Anatomie Comparee,' where the true trans- 

 verse processes of the occipital vertebra, though exogenous, like those of the 

 succeeding trunk-vertebrae in man, had become developed to an equal extent 

 with such transverse processes ; the abnormality of the human occipital thus 

 repeating its normal condition in the quadruped. They however do not cite 

 these instances, or notice the confusion by their author of the true mastoid 

 with the paroccipital in reference to this his first objection to the vertebral 

 homology of the occipital segment. But it might further have been re- 

 marked, in respect of the segment of the skull to which the mastoid really 

 stands in parapophysial relation, that although the mastoid belongs in man to 

 the petrosal in the sense of being anchylosed with it, it articulates with the 

 parietal ; and the persistence or obliteration of a primitive suture is too vari- 

 able a phenomenon to determine to which of two bones a third connected with 

 both essentially belongs. The constant existence of the paroccipital either 

 as an autogenous element or an exogenous transverse process in all the 

 oviparous vertebrate classes, its common existence in mammals, and occa- 

 sional, though rare, development in man, establish that additional, though 

 by no means essential vertebral character in the occipital segment, which 



lo'idiens et les deux moities de l'anneau de l'atlas a la couvrir. Les condyles sont repre- 

 sentes par les facettes articulaires au moyen desquelles l'atlas s'unit a, l'axis. Le trou con- 

 dylien qui laisse passer le nerf de la neuvieme pair, a quelque rapport avec le trou de l'atlas 

 qui laisse passer le premier nerf cervical, et la premiere courbure de l'artere vertebrate. On 

 a aussi trouve quelque rapport entre l'apophyse mastoide qui, dans la plupart des animaux, 

 appartient a l'occipital, et l'apophyse transverse de l'atlas et des autres vertebres ; sur quoi 

 il faut remarquer que ces rapports sont nioindres dans l'homrae a certains egards que dans 

 les quadrupedes, puisque l'atlas n'y a ordinairement qu'une echancrure pour le passage de 

 l'artere et que l'apophyse masto'ide y'appartient entierement au rocher." — I. c. p. 710. 



* " On pourrait meme comparer l'occipital superieur aux apophyses epineuses qui, dans 

 certains animaux, naissent par des points d'ossification particuliers, et restent quelque temps 

 distincts du reste de la vertebre; cependant il y aurait deja ici une grande difference de struc- 

 ture et de fonction." — I. c. p. 711. 



f " Ces resemblances etaient naturelles a attendre dans la partie de la tete placee a l'extre- 

 mite de la colonne vertebrale, et dout les fonctions sont en effet analogues a celles des ver- 

 tebres puisqu'elle laisse passer comme elles le grand tronc medullaire." — I. c. p. 711. 



X Cuvier, e. g. describes this element as " L'apophyse mastoide, qui est tres-longue, tres- 

 pointue et toute de l'occipital," in his elaborate Ossemens des Cochons, Oss. Fossiles, t. ii. 

 pt. i. p. 117. 



