ON MOLLUSCS IN GENERAL 1 . 



IN what precedes we have treated of the greater part of those 

 animals that have no internal skeleton or no vertebrae. There still 

 remain however for our consideration many that, in the system of 

 Linnceus, were referred to the class of worms, but which by CUVIER 

 were, first as a class, afterwards as a larger group constituting a 

 primary form (typus), collected together and separated from the rest 

 of the worms 2 . Since they do in reality form such a group, which 



1 Compare on this division of the Animal Kingdom, amongst others : 



M. LISTER Exercitatio anatomica de Cochleis maxime terrestribus et Limacibus. 

 Londini, 1694, 8vo. 



Ejusd. Hist, sive Synopsis method. Conchyliorum et Tabularum anatomicarum editio 

 altera. Recensuit et indicibus auxit G. HUDESFORD, Oxonii, 1770, folio. 



M. ADANSON Hist, natur. du Senegal. Coquillages. Avec 19 pi. Paris, 1757, 4to. 



J. X. POLI Testacea utriusque Sicilies eorumque historia et anatome, Tabulis cen. 

 illustrata. Parmse, fol. Tom. I. 1791, Tom. n. 1795, Tom. in. Pars prima posthuma ; 

 edid. S. DELLE CHIAJE, Parmse, 1826, Pars altera, auctore S. DELLE CHIAJE, Parmae, 

 1827 (this part remains unfinished). 



CUVIER Memoires pour servir a VHistoire et a VAnatomie des Mollusques, avec 

 35 PI. Paris, 1817, 4to. 



E. FORBES and S. HANLEY Nat. Hist, of British Mollusca and their Shells. 

 London, 1848 50, 8vo. 



G. JOHNSTON An Introd. to Conchology ; or Elements of the natural Hist, of 

 Molluscous Animals. London, 1850, Svo. 



As manuals the following especially may be consulted : 



LAMARCK Hist. nat. des Animaux sans Vertebres, ie tdit. par DESHATES et 

 MILNE EDWARDS, Tom. vi. 1835 ; H. DUCROTAY DE BLATNVILLE Manuel de Malaco- 

 logie et de Conchologie, i Vol. 8vo, Paris et Strasbourg, 1825 1827, avec 107 Planches, 

 and G. P. DESHAYES Traite eUmentaire de Conchologie, Paris, 1838 and foil. 8vo. 

 (hitherto only 9 numbers have appeared). We shall principally refer to these two 

 last works, besides GUERIN'S Iconographie, for the figures, and only occasionally quote 

 more extensive works of plates, as those of MARTINI and CHEMNITZ, KIENER, &c. 



2 See p. 33 and 208. To the works of CUVIER referred to in the last of these 

 pages, there ought to have been added one that was printed separately from the 

 Decade philosophique, a journal with which I am not further acquainted, and which 

 now lies before me : it is entitled, Memoire sur la structure interne et externc et sur leg 



