Mr C. Collier 07i Umvalves. 233 



ployed for the genera ? Who, taking up a murex, or cypraea, or 

 stromhus, or buccinum, or bulla, could, from the application, 

 be led to the generic features of the shell ? Who is not forced 

 to charge his memory with this, as with the specific name? 



By parts or conditions peculiar to univalves, I propose to dis- 

 tinguish and nominate families : to divide into sub-genera or 

 sub families such as are distinguished by an uniform state * of 

 the more general feature, and to separate into individuals such 

 as, with this peculiar state, have additional parts, or modifica- 

 tions of such parts. To simplify the nomenclature, and render 

 it more perspicuous, I suggest Latin derivations exclusively, 

 and these to be adjectives, and of one termination. Were this 

 base considered substantial, a correction of the individuals might 

 also be made ; for these, like the genera, are diffuse and vague, 

 the same principles might determine their denomination from 

 essential distinguishing features f; next, from difference of 

 colour or size ; lastly, these faihng, from similitude with other 

 objects. 



The parts and conditions chosen for generic distincticm and 

 denomination are: Cavity, lip, columella, rostrum or heah, 

 spire, open, tubular. 



1. The coverings of cephalopodous mollusca+ assume, ante- 

 riorly, a locular or chambered form, with or without, to use the 

 language of conchology, dissepiments ; that is, in one, or divid- 

 ed into more cavities. It may be objected to the adoption of 

 this latter, that the fact cannot be known without a section of 

 the shell ; but the transparent walls of the smaller species {Li- 

 tuus spiralis) allow examination, and inference may thus be 

 made, besides knowledge of the fact, that the structure within 



• Rostratum. The generic appellation for all shells furnished with a ros- 

 trum, divided into three sub-genera from the state of that feature ; a, straight 

 out ; b, turned to the right, or from the columella ; c, turned to the left, or 

 with the columella. 



t The first of the conditions is well exemplified in Murex Tribulus, aptly 

 named after its thorny processes. The second is neither commonly or rigidly 

 fulfilled: Murex Gii/as, Buccinum patulum. The last is, and sometimes 

 happily, employed : Turbo scalaris, Cyproea Caput-serpcntis, Bulla Ooum, &c. 



t Division Testaces : Fani. Cephalopodes : Cinquieme Tableau, Cuvier. 



2 



