394 HETEEOPHEOSYNID^E. 



discrepancies. Philippi unaccountably omits all mention of 

 the principal peculiarity, the curious operculum, but he does 

 say that the animal departs somewhat from those Rissoae 

 he has examined, both as regards the organs and the shell ; 

 and I add, that with the exception of the very short muzzle 

 and depressed line in the after-part of the foot, there is not 

 another external organ that has much concordance with the 

 typical RisscKB. 



Neither can it be associated with Jeffreysia, which indeed 

 agrees with it, essentially, in respect to the operculum ; but 

 the animals of the two are very different. I have therefore 

 proposed for it a new genus, which ought, I think, with Jef- 

 freysia, to form a family intermediate to the Littorinidee and 

 Pyramidellidae. I have omitted to mention that M. D'Or- 

 bigny's subgenus Rissoina cannot receive it, as with a testa- 

 ceous operculum and apophysis, it is of the spiral or Littorini- 

 dan type, whilst the present object is of subannular elements ; 

 and I consider the operculum, though so much neglected, to 

 afford a most important generic and differential diagnosis; 

 but independent of these points, I could not, agreeably to my 

 views, accord with such an allocation. I repudiate all sub- 

 genera, which I consider as an awkward attempt to define what 

 is undefinable an intermediate condition between a genus and 

 a species. I think, when a species is so discordant with the 

 generic type, that it ought to merge elsewhere, and take on a 

 substantive capacity and become the type of a new genus. 

 There can be no objection to the term sub when used ad- 

 jectively to qualify a word, as subannular, subrotund, and 

 subsymmetrical, &c., but not substantively , as then it be- 

 comes the source of innumerable absurdities : with me a 

 genus has no intermediate state beyond species and their 

 varieties. 



I would therefore submit to malacologists, as I have 

 shown that no existing genus can with propriety receive this 

 curious creature, that a new one be constituted for it, and en- 

 titled Barleeia, as a just recollection of the exertions of a gen- 

 tleman who loses no opportunity of enriching science with 

 living objects from the Great Book of Nature ; and though 



