252 CLASSIFICATION. 



CLASSIFICATION. 



A detailed history of tlie progress of the science of conchologj^ 

 from the most ancient period to the present time, would be both 

 interesting and instructive : want of space prevents the insertion 

 of such an account here. 



The following rapid sketch of the history of the modern 

 classification of mollusks and exposition of 'a system, based 

 principally on the lingual armature of the gastropods, is trans- 

 lated and condensed from a paper by the late Prof. Morch, 

 published in the Journal de Conchyliologie (xv, 232, ISGT). 



Ancient authors classified shells according to external forms, 

 from which they derived generic names. Linnseus was the first 

 to introduce characters independent of the form of the shell ; as 

 the teeth and ligament in bivalves, plications and sulcations in 

 univalves. By these characters Voluta and Turbinella were 

 separated from Murex, Buccinnm, etc. 



Linneeus classed the species of each genus, according to the 

 height of the spire, in analooous sections, of which the most 

 were adopted by Bruguiere as distinct genera. Thus the following- 

 genera were terminated by a section " turrita," Bulla by Achatina ; 

 Buccinum by Terebra ; Strombus by Potamides and Pirena ; 

 Murex by the spiny Cerithise ; Trochus by Telescopium and 

 Pyramidella ; Turbo by Turritella ; Helix by Melania and 

 Limnrea. 



Linnseus was the first to take the form of the animal into 

 consideration as a generic character ; but he indicated only five 

 different t^q^es of animals, namel}^; Doris, Limax, Tethys, Sepia, 

 and Ascidia. Thus the animal of Chiton is a Doris, that of 

 Argonauta a Sepia ; bivalves with simple mantle are Ascidise 

 (Solen, Mya, Pholas), and those with fringed mantle Tethys. 

 Nearly all the univalves are called Limax. 



Adanson must be regarded as the founder of Malacology, but 

 the number of mollusca known in his time was too few to permit 

 the elimination of the principal systematic divisions. He was 

 also the first to take into consideration the operculum and the 

 shell structure as characters, and to divide the biyalves according 

 to the number of muscular impressions. 



The system of Cuvier, based on the respiratory organs, 

 induced a great reform in Conchology. The shells of pulmonate 

 mollusks, heretofore dispersed by all authors, with the exception 

 of Adanson, among the pectinibranchs, were assembled in one 

 group, which still remains intact. Although it may be diflScult 

 to indicate by a description the difi"erence which exists between 

 the shell of a pulmonate and that of a branchiate mollusk, there 

 are, nevertheless, few collectors who will not recognize it at 



