TROCIIATELLA. 305 



Genus TRQCHATELLA, Swainson. 



Operculum non-spiral, semi-oval, flat, pale, more or less 

 solid, horny. 



Shell trochiform or globosely-conical ; aperture sub- tri- 

 angularly semi-oval; columella somewhat flattened, not 

 emitting a callus at the base ; margins of the peristome 

 joined by a very thin, not diffuse callus. 



Ex. T. pulchella, Gray, pi. 87, fig. 5. Operculum, T. 

 pulchella, fig. 5, a, 5, b. 



The West-Indian Islands and Tropical America are the 

 countries that harbour these beautifully-constructed shells, 

 which are at once known by their sub-trochoid form, their 

 expanded peristome, and by the base not being callous 

 beneath. 



Species of Trochatella. 



chrysostoma, Shuttl. Petitiana, D'Orb. 



conica, Pfeiff. pulchella, Gray. 



costellata, Morel. rupestris, Pfeiff. 



elegantula, Pfeiff. semilirata, Pfeiff. 



Gaudiana, Pfeiff. Sloanei, D'Orb. 



Grayana, Pfeiff. stellata, Velasq. 



Josephinae, C. B. Adams. Tankervillii, Gray. 



Moquiniana, Eeclnz. tenuis, C. B. Adams. 



opima, Shuttl. virginea, Lea. 



Sub-gen. viana, H. and A. Adams. 



Shell ecarinate, with the right margin of the peristome 

 sinuate d. 



regina, Morel. sagra, D'Orb. 



