CRUCIBULUM. 



365 



the name of Lithedaphus. The form of the internal tes- 

 taceous appendage, adhering at the base, with the sides 

 free, and seraiconical, as if longitudinally divided, will 

 at once distinguish the genus from all the others of the 

 family; the surface of the shell is rugose or cancellated 

 the species are found in all parts of the world. 



Species of Calyptra. 



cepacea, Brod. 



chlorina, Gould. 



cornea, Brod. 



corrugata, Brod. 



depressa, Adams and Reeve. 



equestris, Linn. 

 planulata, C. B. Adams. 

 tectum-Sinense, Chem. 

 varia, Brod. 



Genus CRUCIBULUM, Schumacher. 



Buccal appendages obtuse and truncate; foot circular. 



Shell subconic ; apex subcentral ; aperture wide, with 

 the internal appendage entire and cup-shaped, attached 

 by one of its sides. 



Syn. Biconia, Sivains. Bicatillus, Swains. Caly- 

 peopsis, Brod., not Less. 



Ex. C. rugosum, Deshayes, pi. 40, fig. 4. Shell, C. 

 extiuctorum, Sowerby, fig. 4, a. 



The species of this genus, which is distinguished from 

 Calyptra by the entire, cup-like inner appendage, are 

 generally found attached to other shells ; they are chiefly 

 natives of Western America and the West Indian Islands. 



