292 PKOCEEDINGS OF THE MALACOLOGICAL SOCIETT. 



In Trivia (Fig. 2) the median tooth lias a small pointed central 

 cusp, with four or five small and slightly curved ones on each side 

 of it, while the marginals have no small cusps, but are of such a 

 length that they almost meet in front of the median tooth, and the 

 laterals have 3-5 small cusps situated on each side of the central one. 



With a view to ascertaining whether the- differences in the nervous 

 svstem and dentition mentioned above were sufficient to justify generic 

 separation, I submitted the question to Professor G. C. Bourne, whom 

 I wish to thank for his kindness in this and other matters connected 

 with this paper. He maintains that the ditfei-ence in the nervous 

 system alone is sufficient for separation, and this, together with that 

 of the dentition, leaves no doubt that they should be considered as 

 separate genera. The justification for this conclusion will, it is 

 hoped, be obvious when the differences of nerve systems, radute, and 

 shells are taken into consideration. 



Much discussion has arisen as to whether Bolten's " Museum 

 Boltenianum," 1798, Humphrey's " Museum Calonnianum," 1797, 

 Meuschen's "Index Musei Gronoviani," 1778, and the "Museum 

 Geversianum," 1787, also of Meuschen, ought to be accepted. After 

 getting the opinion of several of the chief authorities on conchology 

 and nomenclature, and after having studied the works themselves and 

 various criticisms, and the reasons for and against accepting them, 

 I have come to the conclusion that the opinion held by Mr. E. A. Smith 

 and Professor W. H. Dall is correct, and I therefore propose adopting it. 



1. Bolten must be accepted, as he quoted the names and figures 

 with pages, plates, and volume of previous authors, and was strictly 

 binomial, although he gave no diagnoses of the various species. 



2. The "Museum Calonnianum" ought to be entirely ignored; 

 it is simply a sale catalogue, Humphrey's name did not appear on it, 

 and there are no references. 



3. Both of Meuschen's publications ought also to be debarred from 

 zoological literature, as he did not use a strictly binomial, but in 

 places a trinomial, system, and his generic names, of which I qiiote 

 four, viz., Cassides, Gloiosce, Coni, and PorcellancB, would not now be 

 allowed as generic appellations. For these reasons it is undesirable 

 to accept his works. 



Owing to the reasons already stated for not admitting Meuschen, 



