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CONCHOLOGY. 



History. 



Adxnson's 

 arrange- 

 ment. 



CLASSE I. L1MA9ONS. 



J,innseus, 

 1766. 



Sect. I. Limagons Univalves. 



Fam. 1. Les limagons univalves qui n'ont ni yeux ni 



cornes. 

 Fam. 2. Les limagons univalve qui ont deux cornes, et 



les yeux places a leur racine et sur leur cote interne. 

 Fam. 3. Les limagons univalves qui ont quatres cornes, 



dont les deux exterieurs portent les yeux sur le som- 



met. 

 Fam. 4. Les limagons univalves qui ont deux cornes, 



et les yeux places a leurs racines, et sur le cote ex- 



terne, ou par derriere. 

 Fam. 5. Les limagons univalves qui ont deux cornes et 



les yeux poses un peu au-dessus de leur racine, et 



sur leur cote externe. 



Sect. II. Limagons Opercules. 



Fam. 1. Limagons opercules qui ont deux cornes, avec 

 un renflement, et qui portent les yeux ordinairment 

 au-dessus de leur racine, et a leur cote externe. 



Fam. 2. Limagons opercules qui ont deux cornes sans 

 renflement, et les yeux places a leur racine, et siu' 

 leur cote externe. 



Fam. 3. Limagons opercules, qui ont quatres cornes, 

 dont les deux exterieures portent les yeux sur leur 

 sommet. 



Classe II. Les Conques Bivalves. 



Fam. 1 . Les conques bivalve, qui ont les deux lobes du 



manteau separes, dans tout leur contour. 

 Fam. 2. Les conques bivalves dont les deux lobes du 



manteau forment trois ouvertures sans aucun tuyau. 

 Fam. 3. Les conques bivalves dont les deux lobes du 



manteau forment trois ouvertures dont deux pren- 



nent la figure d'un tuyau assez long. 



Classe III. Les Conques Multivalves. 



Fam. 1. Les conques multivalves, dontaucune des pie- 

 ces de la coquille ne prend la forme d'un tuyau. 



Fam. 2. Les conques multivalves, dont une des pieces 

 de la coquille prend la forme d'un tuyau qui enve- 

 loppe entierement toutes les autres. 



We come now to take a short view of the concholo-, 

 gical labours of Linnaeus. Considering his comprehen- 

 sive genius, and the accurate views which he had with 

 respect to arrangement, the world might have expect- 

 ed from his pen, a system freed from the imperfections 

 which might have been observed in the productions 

 of his predecessors, and at once obvious, simple, and 

 convenient. That Linnaeus fell far short of this, every 

 one knows, who has paid any attention to the subject. 

 Before the days of Linnaeus, the secondary divisions of 

 testaceous bodies were by far too numerous, and the 

 characters of the genera and species vague and inaccu- 

 rate. In attempting to avoid the former error, Lin- 

 naeus greatly reduced all the ancient subdivisions, and 

 even genera, and over-reached that useful simplicity 

 which he had in view. But the greatest praise is due 

 to this illustrious naturalist, for having employed, in 

 the construction of his generic and specific characters, 

 terms which were precise and applicable ; and hence, 

 his genera and species have acquired a stability which 

 conchologists knew not before. 



The primary divisions of Linnaeus were such as had 



been in common use. He employed the divisions, uni- 

 valves, and bivalves of Aristotle, and the plurivalves of 

 Major, under the title of multivalves. And, in con- 

 formity with the general distribution of animals in his 

 system, he placed the most complex shells, or the mul- 

 tivalves, at the beginning, and the univalves at the 

 end. In the first arrangement of testaceous bodies, 

 Linnaeus only employed eight genera, Cochlea, Nauti- 

 lus, Cyprcea, Haliotis, Patella, Dentalium, Concha, and 

 Lepas. In the twelfth edition, shells are distributed 

 as follows : 



History. 





I. M 



ULTIVALVIA. 



Linnseaa 



Gen. 



Chiton. 

 Lepas. 



Gen. Pholas. 



arrange. 





II. BlVALVIA CONCH.E. 





Gen. 



Mya. 



Gen. Spondyhte- 







Solen. 



Chama. 







Tellina. 



Area. 







Cardium. 



Ostrea. 







Mactra. 



Anomia. 







Donax. 



Mytilus; 







Venus. 



Pinna. 







III. 



Univalvia. 







* Spira rcgulari Cochlea. 





Gen. 



Argonauta. 



Gen. Strombus. 







Nautilus. 



Murex. 







Conus. 



Trochus. 







Cyprea. 



Turbo. 







Bulla. 



Helix. 







Voluta. 



Nerita. 







Buccinum. 



Haliotis. 







** Absque spira regulari. 





Gen 



. Patella. 



Gen. Teredo. 







Dentalium. 



Sabella. 







Serpula. 







This system, so much admired by the disciples of Remark* 

 Linnaeus, labours under several imperfections. At- on the Lift 

 tending principally to the shells themselves, he, in a naau ar. 

 great measure, overlooked the contained inhabitant. rangemq»t 

 Great pains are taken to give a description of a regu- 

 larly shaped piece of carbonate of lime, while the ani- 

 mal in the description of the species is totally over- 

 looked. We are aware, that, in the definition of the 

 genera, the animals inhabiting each genus are referred 

 to one or other of the molluscous genera. But these 

 references are as absurd as they are useless. In vain 

 will the student of nature look for the two tentacula 

 and the fine fringed anus of the Dorris, in the species 

 of the genus Chiton, which have no tentacula, and 

 whose anus is placed at the posterior extremity ; or for 

 the four tentacula of the Limax, in the aquatic species 

 of the Linnaean genera of Turbo and Helix. Linnaeus 

 states, as part of the character of his genus Limax: 

 " Foramen laterale dextrum. tentacula quaiuor." Now, 

 in all the aquatic species of Helices, only two tentacula 

 can be observed ; and in the reversed Turbines, the la- 

 teral pore is situated on the left side. Yet, the animals 

 of those shells are referred to the genus Limax, by Lin- 

 naeus himself! Innumerable instances of the same kind 

 could be produced, to shew that the Linnaean arrange- 

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