130 



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

 may be proved really to belong to a different genus ; and when 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, with the synonyma belonging 

 to that type. The type on which the genus or subgenus, as it may 

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

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

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

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

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

 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 like Linnaeus'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 which he has figured ; the latter is the course that I have adopted 

 with respect to Risso's work, whose 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 type which the earliest 

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

 Trochus niloticus as the type of Trochus, 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 plates 

 of the Fundamenta Testaceologice (Amcen. Acad. viii. 1785, 107) of 

 Linnceus 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 Area, four of Patella, three of Cypraa, four of 

 Murex, five of Trochus, three of Strombus, and two 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, Donax scripta of Donax, 

 Chama gigas of Chama, Buccinum Harpa of Buccinum, Mya pictorum 

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

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

 with his characters, and to have adopted which would have greatly 

 confused the science. 



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

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

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

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



