48 
MOLIiUSCA. 
pieces of bone, it is found in almost every sea, where it lives on 
cozy bottoms. 
M. de Lamarck leaves the name of Bulla*, to those species whose 
shell, merely covered with a slight epidermis, is large enough to 
shelter the animal. It is somewhat more convoluted than in Bulleea. 
Bulla lignaria,^^.-. Martini, I, xxi, 194,95; Cuv., Ann. du 
Mus.,XVi, 1 ; Pol. Test. Neap., Ill, pi. xlvi. (The Wafer.) The 
oblong shell with its concealed spire and ample aperture, very 
wide anteriorly, resembles a loosely rolled lamina, streaked in 
the direction of its whorls. The stomach of the animal is armed 
with two large semi-oval osseous pieces, and with a small com- 
pressed onef. 
Bulla ampulla, L,; Martini, I, xxii, 20, 204; Cuv., Ann. du 
Mus., XVI, 1. (The Nutmeg). The shell oval, thick, clouded 
with grey and brown ; the stomacli furnished with three black, 
very convex, rhomboidal pieces. 
Bulla Hydatis, L, ; Chemn. IX, cxviii, 1019; Cuv., Ann. du 
Mus., XVI, 1. (The Water Drop.) Shell round, thin, and semi- 
diaphanous ; the last whorl, and consequently the aperture, 
higher than the spire ; three small scutelliform pieces in the 
gizzardj. 
We reserve the name of Akkra, properly so called, Doridium, 
Mech., Lobaria, Blainv., for those species which have no shell what- 
ever, or only a vestige of one behind, although their mantle has its 
external form. 
A small species. Bulla carnosa, Cuv., Ann. du Mus., XVI, 1 ; 
Meek., Anat. Compar., II, vii, 1, 3; Blainv. Malac., pi. xlv, f. 
3, is found in the Mediterranean. The only armature of the 
stomach is the mantle ; its fleshy oesophagus is extremely thick. 
A tuberculous species, Doridium Meckelii, Delle Chiaie, Me- 
mor.,pl. X, f. 1 — 5, inhabits the same sea. The 
Gastropteron, Meckel. 
Appear to be Akerae, the margin of whose foot is extended into 
broad wings, used in natation, which they effect on their back. It 
has no shell, nor has the stomach any armature ; a slight fold of skin 
is the only vestige of branchial operculum that is perceptible. 
* The genus Bulla, Lin., not only comprised tJie Aktra, but also the Auricula, 
Agatina, Physce, Ovula and Terebella, animals between which there is much difference. 
Brugieres commenced the work of reformation by separating the Agutina and the 
Auricula, which he united to the Lymnei in the genus Bulimus ; M. de Lamarck 
finished it by creating all the genera we have just named. 
•f- Gioeni having observed this stomach separate from the animal, mistook it for 
a shell, and made a genus of it, to which he gave his own name (The Tricla of 
Retzius, Char, Brug.). Gioeni even went so far as to describe its pretended habits. 
Draparnaud was the first who perceived this mixture of error and fraud. 
I Add, Bulla naucum ; — Bulla physis. Muller describes smaller ones, such as the 
Akera bullata, Zool. Dan., LXXI, or Bulla akera, Gm. 
