The following information was prepared by Graham Oliver (1999).
Lewis Weston Dillwyn plays an important role in early molluscan nomenclature through his 2 volume "Descriptive Catalogue of Recent Shells" published in 1817. The primary significance is its first valid binomial use of many of the names in Martini and Chemnitz.
Confusion has arisen through the belief that for species taxa bearing Dillwyn's authority the type specimens will be in his collection, here in Cardiff. This is not the case and the types are to be found in those collections related to the original names.
For those validating Chemnitz the types are most likely to be found in the Zoological Museum, Copenhagen.
The Museum does hold the Dillwyn collection and it is believed to be the "Small cabinet of shells" mentioned by Dillwyn in the preface to his publication.
This collection by no means represents the taxa in his Catalogue and in general is poorly labelled. It was reviewed by J. Davy Dean in 1936 (Journal of Conchology, volume 20: 230-232) and he selected four lectotypes:-
Venus tiara Dillwyn: Descript. Catalogue, 1817, vol.1, p. 162
Bullia cochlidium (Dillwyn): Descript. Catalogue, 1817, vol.2, p. 627
This shell is referred to a figure in Chemnitz vol. 11, p. 275, t. 209, f. 2053/4 and consequently gives rise to concern about the validity of the designation. This requires further research.
Murex scoloplax Dillwyn: Descript. Catalogue, 1817, vol.2, p. 681
Distrorsio mulus (Dillwyn): Descript. Catalogue, 1817, vol 2, p. 704
Should original material for those taxa validated by Dillwyn but not described by him not be available it may be justifiable to use the Dillwyn collection as a source of neotypes. We would welcome consultation and enquiries should your research begin to lead in that direction.