316 repo'rt— 1846. 



The new functions which the uplifted and independent spines of the pari- 

 etal and frontal vertebrae perforin in man and many mammals are, with 

 respect to the parietal bones, to shield the upper surface of the middle and 

 posterior parts of the cerebral hemispheres, whilst the frontal is confined to 

 covering the anterior lobes of the same hemispheres. 



Hereupon it may be asked whether such relations and offices are the rule 

 or only the exception ; and, if the latter, whether it occurs in the lowest or 

 the highest of the vertebrate series ; whether in that class where the arche- 

 typal arrangement of parts is most, or in that in which it is least departed 

 from ? All these considerations are felt to be indispensable by the homo- 

 logist in quest of the true signification of the parts of the animal frame, 

 before drawing his conclusions from the first modification that may present 

 itself. They are neglected by Cuvier in the objection to the vertebral cha- 

 racter of Oken's 'kiefer-wirbel,' founded upon the relations which the parietal 

 bones present to the encephalon in the mammalian class. Yet the more 

 normal relations of those bones, both to the encephalon and to the alisphe- 

 noids, seem to have been present to the mind of Cuvier, and to have been 

 duly appreciated by him when he defined, in 1817, the second cranial cinc- 

 ture as constituted by the parietals and sphenoid*. 



With regard then to the first of Cuvier's arguments for viewing the human 

 and mammalian parietals as ' des pieces particulieres qui ont une destination 

 particuliere,' viz. that they are separated from the alisphenoids by the tem- 

 poral bones. If we commence our consideration of it by the question, whether 

 this separation be the rule or the exception, the reply which Nature sanc- 

 tions will be that they are not so separated in any of the three great classes of 

 oviparous vertebrata, nor in the majority of mammalia, nor even, as a general 

 rule, in man himself. With regard to the second objection founded on the 

 interposition of the enormously and backwardly developed prosencephalon 

 between the mesencephalic spines (fig. 25, 7) and the mesencephalic segment - 

 of the brain, to which the parietal vertebra essentially relates, — its value will 

 depend on the choice made by the nomologist between the function of the 

 parietals as immediate shields to the optic lobes (mesencephalon) in the cold- 

 blooded classes, and their function as mediate ones through the interposed 

 mass of the prosencephalon in the warm-blooded classes, a* that which best 

 manifests adhesion to the ideal archetype. What to me has ever appeared one 

 of the most beautiful and marvellous instances of the harmony and simplicity 

 of means b) r which the One great Cause of all organization has effected every 

 requisite arrangement under every variety of development, is the fact, that 

 the protection of the enormous cerebrum peculiar to the higher mammals 

 has not been provided for by new bones : by bones, e. g. developed from 

 centres so numerous or so situated as to render any determination of their 

 homologies as vague and unsatisfactory as would result from the attempt to 

 determine those of the dermal ossifications upon the head of the sturgeon, in 

 reference to the endoskeletal epicranial bones in fishes and reptiles. We 

 might well have expected, had conformity to type not been a recognizable 

 principle in the scheme of organized beings, to have had so many ' particular 

 bony pieces' and so situated in the expanded human cranium as would have 

 baffled all our endeavours to reduce them to the type of the epicranial bones 

 of the reptile or fish. Yet the researches of the great comparative anatomists 

 of the present century, and more especially those of Cuvier himself, have 

 proved that there is no such difficulty : and a glance at the Table of Special 

 Homologies, No. 1, will show that the bones (3, 7, 11) most modified in rela- 

 tion to the expanded cerebrum and cerebellum of man and mammals are 

 * Regne Animal, i. p. 73. 



