Natural^Historical Collections. 227 



fiition, each of these elements being easily determined. Thus the principle pro- 

 piosed for the composition of a vertebra, or a vertebral apparatus, in the higher 

 animals and the articulated animals is completely confirmed, and is moreover 

 enriched with positive proofs. 



2. M. Geoffrey St. Hilaire had advanced that the molluscous animal must be 

 contained within its vertebra ; and it has been found by examination that it is 

 actuaUy contained in a single solid apparatus, which furnishes the positive ele- 

 ments of the vertebra. 



3. Tliis result of a single vertebra is decisive, and depends upon the organiza- 

 tion of the moUusca, which are destitute of solid organs of sense or locomotion, 

 these parts not being necessary to them. 



4. The solid organization of the molluscous animals, compared with that of the 

 articulated animals, enables us to see the advantage which those zoologists have, 

 who, in their attempts at classification, have given to these organs a superiority over 

 the other apparatus. In our days it has been attempted to debase the Crustacea, 

 and more particularly insects, beneath the moUusca. But it has been found that 

 along the course of the digestive canal of the insect, there occur all the intestinal 

 and glandular parts of the higher animals. The Crustacea have been shown to 

 possess a very complex circulatory apparatus, of a higher order than that of the 

 conchifera. As to the nervous system in them, there can be no comparison be- 

 tween it and that of the latter, which is so greatly inferior. The circumstance 

 tliat several acquatic larvae respire by branchiae, is of itself decisive as to the su. 

 periority of the articulated animals with regard to the respiratory system, it be- 

 ing a constant rule that organization proceeds from the simple to the complex. 

 If all the facts observed tend to demonstrate that the more energy an animal pos- 

 sesses, the more active and powerful is its respiration, who will now venture to as- 

 sert that the respiration bf insects yields to that of an oyster ? Thus the mol- 

 luscous animal is inferior in these various respects. 



5. Whatever name may be employed for the calcareous apparatus of the mol- 

 luscous animals, there is a perfect similarity between it and the calcareous ap- 

 paratus of the articulated animal. In the higher animals each of these apparatus 

 is designated by the name of vertebra, and the same denomination is adopted by 

 the author, although he neither means by the term an apparatus destined for the 

 protection of the spinal marrow, nor considers it strictly applicable to the cranial 

 vault or laryngeal apparatus of the higher animals, but merely designates by it 

 any calcareous apparatus formed of five pairs of elementary parts, which may be 

 infinite in its forms and uses. 



6. The articulated animals are so constituted that their arthromeral and ar- 

 throceral pieces, which form most of their instruments, are the most distant from 

 the basial, the most developed, and the most fractured. They are also the most 

 perfect element^ since in them resides the first perception of external objects and 

 the execution of the will. The molluscous animals are in a condition precisely 

 the reverse. Their arthromeral and arthroceral pieces, which are always formed 

 of a single piece, are internal and very near the basial. These elements do not 

 require to be in connection with external objects ; but their composition is nacre- 

 ous, and formed of finer molecules than the other parts of the shell. The author 

 does not venture to say that these two pairs of elements are connected with nerves 

 possessed of more sensibility, or having a higher degree of incitability ; but he 

 thinks there is every reason to presume that they contain a little more phosphorus 

 than the other parts. 



In fine, it may be remarked that, while there is considerable appearance of 

 truth in this theory of the composition of the solid parts in the moUusca, many 

 other principles might as well correspond with the phenomena exhibited by their 

 structure, as that of the ten pieces of a vertebra : those of the tubular, the spheri- 

 cal, or the prismatic forms, for example ; and any number below the decimal, will 

 be found to have as many correspondences in the series of animal organization as 

 that selected by the author. If a shell so homogenous in its structure as that of the 

 limpet is resolvable, by analogy or imagination, into three layers, and several 



