312 REPORT—1846. q 
although its ‘annular part’ is closed above by a transverse plate*. instead of 
by a vertical spine, of which, indeed, there remains hardly more vestige than _ 
is presented by the tubercle or rudiment of the spinous process in the supra- 
occipital of man. It must also be remembered, that the human supraoccipital 
does retain to a certain extent the same function in relation to the attach- 
ment of the proper vertebral muscles (splenii capitis, complexi, and the modi- 
fied interspinales called ‘recti capitis postici maj. et min.) as the succeeding 
vertebral spines; and combines this with the same place of completing, as 
the key-stone, the neural arch; although by reason of the more voluminously 
developed segment of the neural axis protected by that arch the peripheral ele- 
ment is chiefly modified for the acquisition of the required increase of space.’ 
Cuvier next proceeds to comment on Oken’s endeavour to represent the 
basisphenoid and the two alisphenoids with the two parietals as forming a ver- 
tebra: and he admits that there is some analogy, though this is much more 
feeble than the differences. ‘The basisphenoid, having another function, 
takes on a different form from the basioccipital, especially above, by virtue : 
of the posterior clinoid processes: and in the embryo it is composed not of 
a single nucleus, but of twot+.” With respect to the objection from the 
modification of form alluded to, it may be remarked that the same element 
in other vertebral segments of the body undergoes much greater change 
of shape; the centrums of the lower cervical vertebra in many birds send down 
two processes as well-marked as the ascending ones called ‘ clinoid’ in that 
of the parietal vertebra, not to speak of the ‘soc de charrue’ of the coccy- 
geal vertebre of the bird, for example, without any difficulty having been felt 
or expressed by Cuvier in their recognition as modified vertebral bodies, the 
more essential characters of their general homology being as plainly retained 
as in the case of the basisphenoid ; in its relation, e. g. to the neur- 
apophyses and the support of the mesencephalon. With regard to the 
objection from the two centres of development, if this be valid against the 
general homology of the basisphenoid (6, fig. 25) as a vertebral centrum, it 
equally tells against the body of the atlas (¢), which, as Cuvier well knew, 
was ossified sometimes from two, and sometimes from three centres{. And 
I may further observe that, although Cuvier affirms the two ossifie centres of 
the basisphenoid to retain for a long time between them simple cartilages, 
my observations bear out the accuracy of the remark of Kerkringius, (whose 
figures Cuvier cites,) touching the “ dua ossicula distincta” (tab. xxxiv. fig. 
iii. c, c), viz. “que celerrimé in formam figure apposite K coalescunt”: 
and the figure of the coalesced rudiments of the basisphenoid given by Kerkrin- 
gius closely resembles the bilobed rudiment of the vertebral centrums in the 
sacrum of the chick. 
Cuvier next objects to the neurapophysial character of the alisphenoids, 
that the ‘foramen ovale’ is rarely a notch, more often a complete hole. 
* “ Tes vertébres. L’atlas est composé de six pieces, &c.—La premiere, a, est une lame 
transverse qui fait le dos de la partie annulaire. Elle n’a qu’une créte 4 peine sensible pour 
toute apophyse épineuse.’’—Ossemens Fossiles, t. v. pt. ii. p. 95. 
+ En avant du basilaire se trouve le corps du sphénoide postérieur, aux cdtés duquel ad- 
hérent les deux ailes temporales ou grandes ailes. On a aussi cherché areprésenter ces trois 
pieces comme formant une vertébre avec les deux pariétaux. II reste en effet encore quelque 
analogie, mais beaucoup plus faible, tandis que les différences deviennent plus fortes. Le 
corps du sphénoide a bien l’air d’une répétition du basilaire, mais ayant une autre fonction il 
prende aussi une autreforme, surtout en dessus,au moyen des apophyses clinoides postérieures ; 
et dans les premiers temps du fcetus il n’est pas composé d’un seul noyau, mais de deux, qui 
ont long-temps entre eux de simples cartilages.’’—/. c. p. 712. 
t Legons d’Anat. Comparée, t. i. (1836) p. 174. Meckel has figured the variety of three 
ossific centres in this element of the human atlas in the Ist vol. of his Archiv fir die Phy_ 
siologie, taf. vi. fig. 1. 
