130 



glven the name in a new line, as at some future period that type 

 may be proved really to belong to a difFerent genus ; and \vhen any 

 succeeding author has established a genus on any species which 

 appears to belong to the before-established genus, it is in a similar 

 manner placed under the proper head, -vvith the synonyma belonging 

 to that type. The type on \vhlch the genus or subgenus, as it raay 

 hereafter prove, was founded, is also given, so that if such type at 

 some future period prove to be distinct from the one under vvhich I 

 have placed it, the synonyma of the genus ■vvill be at once seen. 

 But the names \vhich occur under each head are, according to my 

 present views, to be regarded as synonyma of the genus under \vhich 

 they are arranged. 



In respect to Lamarck's ' Systeme,' De Montfort's ' Conchology,' 

 Megerle's ' Essay,' Schumacher's ' New System,' Blainville's ' Ma- 

 nuel,' and other works which only give the genera, and simply men- 

 tion one or two examples as the types of their genus, the species 

 they give as types are here cited ; but in works likę Linnseus's ' Sy- 

 stema Naturae,' and Lamarck's ' Histoire,' which give the species of 

 Mollusca, it is not so easy to determine which species the author in- 

 tended for the type of his genus. In these cases I have chosen either 

 the best known species, or, if the author has given figures, the spe- 

 cies vvhich he has figured ; the latter is the course that I have adopted 

 \vith respect to Risso's work, \vhose genera are so difficult to under- 

 stand. 



In the Linnaean genera in which there is room for doubt, from the 

 miscellaneous character of the species referred to by the author, I 

 have considered the name as restricted to the t}-pe v>hich the earliest 

 author after Linnaeus has quoted for it : thus as Montfort ąuotes 

 Trochus niloticus as the type of Trochvs, and Lamarck Chiton gigas 

 as the type of Chiton, I have regarded these species as the types of 

 the Linnaean genera. This has not been done without consideration, 

 as I was at first inclined to regard the species figured in the platės 

 of the Fundamentą Testaceologia (Amcen. Acad. viii. 1785, 107) of 

 Linneeus which are given as illustrative of the greater number of his 

 genera, and of the terms used in describing them, as the types ; but 

 I do not think that he had any idea of so considering them, for he 

 gives two species of Arca, four of Pateikt, three of Cypraa, four of 

 Murex, five of Trochus, three of Strombus, and t\vo of Anomia ; while 

 the genera Conus, Mytilus and Pinna are not illustrated. Should 

 these figures have been regarded as the types of his genera, then 

 Ostrea pallium would be the type of Ostrea, t>onax scripta of Donax, 

 Chamą gigas of Chamą, Buccinum Harpa of Buccinum, Mya pictorum. 

 of Mya, Solen strigillatus of Solen, and Nautilus Beccaria of Nautilus ; 

 species \vhich certainly are not the best that could be chosen to agree 

 \vith his characters, and to have adopted which \vould have greatly 

 confused the science. 



There is a series of works ■which appeared between the time of 

 Linnseus and Lamarck which added much to the progress of concho- 

 logy, but •vvhich have been overlooked by the conchologists of the La- 

 marckian school, as for example ' Meuschen Museum Geverianum,' 



