OF CONCHOLOGT. 



21 



Mollusks are but secondary, and that it would be wrong to give 

 them a value of first order in matters of classification ? 



We do not mean to say that the study of these characters is 

 fruitless, and that it may not be called upon to render useful 

 services to science. Far from that ! We acknowledge that, 

 thanks to this study, several families have been more clearly de- 

 lineated whose affinities had remained obscure or had been mis- 

 understood. To give but one example, we consider as satis- 

 factory the division of the Toxoglossata, which has consecrated 

 the re-union, so natural, in all respects, of the Cones and Pleuro- 

 tomas. But, if we admit this union, it is because that, to the 

 characters peculiar of the lingual dentition of the Mollusks which 

 compose it, are added other conchological and zoological cha- 

 racters Avhich confirm its value. The study of lingual and 

 buccal dentition may yet be of great use to naturalists in 

 doubtful specific cases, viz., when it becomes necessary to deter- 

 mine the real value of contested species. All this, we willingly 

 admit. We only refuse to admit one thing, which is a system 

 which would make of the lingual dentition a kind of infiillible 

 criterion, and take exclusively this character for a classification 

 that would not take into consideration either the structure and 

 the form of the shell, or of the other more important parts of 

 the organization of the animal. 



We have yet to speak about a few more assertions of Mr. 

 Morch. Concerning the Helicinge, we persist in sajnng that 

 they must be classed in the neighborhood of the Cyclostomi« 

 rather than near the Neritinfe. The faculty that they possess 

 of dissolving the internal partitions of their shells, a faculty pos- 

 sessed equally by the genera iVm^a, JVeritina aiXid Helicina, and 

 which Mr. Morch gives as a reason for putting them in the same 

 division, is far from being peculiar to these three genera. Not 

 speaking of FroHcrjnna and Stoastoma., the Auricula and even 

 a few Helicidae equally possess it. Among the marine species 

 the genera Conus and Cyprcea are endowed with the same fa- 

 culty to a high degree. We even think that this faculty is com- 

 mon to all Mollusks ; they make use of it in greater or less de- 

 gree in the different genera, but that is all the difference, and 

 in the same Avay that they make a synthesis by secreting the 

 elements of their shell; they can also make the analysis, by dis- 

 solving more or less completely a part of the secreted test. This is 

 then no sufficient reason, in our opinion, for placing the Heli- 

 cinge near the Neritinae. 



When Mr. Morch says the Helicinge are distinguished from 

 the Cyclostomae by the absence of a deep median furrow of the 

 foot, he is right, if applied to the genus Cyclostoma, but he is 

 wrong, if he means to include the Cyclophorus and a few other 

 of the numerous genera which without doubt belong to the same 



