198 



invate a still further and more minute investigation, for the purpose 

 of ascertaining if any, and what, subgenera were contained in the 

 more crowded groups of Mitra and Tiara. This investigation Mras 

 carried on, at intervals, for nearly twelve months ; and the result sur- 

 passed my most sanguine expectations. It has convinced me thatnot 

 only does each of the genera of the Mitrance represent analogically 

 the corresponding groups of the Volutina, but that the šame rela- 

 tions can be demonstrated between the minor di^-isions of the genera 

 Tia7-a and those of Mitra : in other w-ords, that these latter represent 

 all the subfamilies and genera of the other Volutid<e, while they pre- 

 serve their own peculiar or generic character. What I have just 

 said on the parallel relations of analogj' between the Mitrana and 

 the Volutid(E, is strictly applicable, in fact, to the genera Mitra and 

 Tiara, the primary di\T[sions of each of which can thus be demon- 

 strated subgenera. Nor is this all : the materials I have been for so 

 many years collecting have enabled me to ascertain, in very many 

 instances, that the variation of the species, in each of these sub- 

 genera, is regulated on precisely the sarae principle. Hence it fol- 

 lows that the two circles of Mitra and Tiara, likę the two divisions 

 of Mr. MacLeay's Petalocera, contain species representing each 

 other, so that if their generic character is not attended to, it is 

 almost impossible to discriminate them even as species. Many in- 

 stances of this extraordinary analog^^ might be mentioned, indepen- 

 dent of that here alluded to, between Mitra Terebralis and Tiara 

 Terebralis. 



" Selecting this shell to illustrate the numbers " Type 4,4", I 

 may observe, that ' Tj^^e 4' signifies that it belongs to the fourth 

 subgenus of Tiara, in ■n'hich group it is the fourth subtype, uniting 

 to Mitra maurą, -vvhich is the fourth subtj'pe of the first or typical 

 subgenus. Mitra maurą, again, as representing this latter shell, 

 conseąuently becomes the fourth subtype of the first or typical sub- 

 genus, and is therefore marked " Type 1, 4." The first figure always 

 denotes the subgenus, and the lašt the station which the species ap- 

 pcEirs to hold in its own subgenus. 



" I am unacquainted "vvith any group in the animal kingdom 

 which demonstrates more fully than this does the law of represen- 

 tation. It may be mentioned, also, that nearly all the divisions I 

 had long ago characterized, from the formation of the shells alone, 

 have more recently been confirmed by a knowledge of their respec- 

 tive animals : a knowledge for which ■vve are entirely indebted to 

 the able naturalists \vho accompanied the French expedition on 

 board the Astrolabe." — W. S. 



Specimens vrere exhibited of several hitherto undescribed Coivries, 

 most of -vvhich have been brought to England within the lašt few 

 years. They vrere accompanied by the following characters and de- 

 scriptions by J. S. Gaskoin, Esq. 



Genus CypKiEA. 

 CrPRiBA FORMOSA. Ci/pr. testd ovato-globulosd, tentii, sericeo-sub- 



