CLASSIFICATION. 57 



Classification. 



The following rapid sketch of the history of the modern clas- 

 sification of mollusks and exposition of the system, based prin- 

 cipally on the lingual armature of the gasteropods, is translated 

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

 in the Journal de Concliyliologie (xv, 232, 1867). 



Ancient authors classified shells according to external forms, 

 from which they derived generic names. Linnaeus 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, Buccinum, etc. 



Linnaeus classed the species of each genus, according to the 

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

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

 ing genera were terminated by a section " turrita," Bulla by 

 Achatina ; Buccinum by Terebra ; Strombus by Potamides and 

 Pirena ; Murex by the spiny Cerithiae ; Trochus by Telesco- 

 pium and Pyramidella ; Turbo by Turritella ; Helix by Melania 

 and Lymnaea. 



Linnaeus was the first to take the form of the animal into con- 

 sideration as a generic character ; but he indicated only five 

 different types of animals, namely : Doris, Limax, Tethys. Sepia, 

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

 Argonauta a Sepia : bivalves with simple mantle are Ascidiae 

 (Solen, M}*a, 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 per- 

 mit 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 bivalves ac- 

 cording to the number of muscular impressions. 



The system of Cuvier, based on the respiratory organs, in- 

 duced a great reform in Conchology. The shells of pulmonate 

 mollusks, heretofore dispersed by all authors, with the excep- 

 tion of Adanson, among the pectinibranchs, were assembled in 

 one group, which still remains intact. Although it may be diffi- 

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