by William Swainson

“ In the selection of generic characters, sufficiently important to separate Ampullaria from Paludina, great difficulty at present exists; as the fundamental principle on which they should be founded (the formation of the animal) is entirely wanting. It is only known that these shells, like the Paludinæ, are furnished with an operculum. ”

“ This is proved from the fact, that among the Naticæ some have horny, and some shelly, opercula: in Phasianella, this part is, in some species, almost flat, in others remarkably convex; in Turbo, Lam. its form is even more variable, and in the present genus a similar uncertainty exists. One species alone has been positively described as having this part shelly, while in two others the operculum is as certainly known to be horny ”

“ A. testâ ovato-globosâ, olivaceâ, fasciis obscuro-purpureis angustis ornatâ; spirâ brevi, levatâ, apice acuto; labii margine tenui; umbilico mediocri. Shell ovate-globose, olive, with narrow bands of obscure purple ”