83 
I do not know of any British fossil species ; But lamarck describes 
ten species decidedly of this genus : B. alhidus, B. citherella, B. tere- 
bellatus, B acicularis, B. nitidus, B. sextonus, B. conulus, B. cla- 
vulus, B. striatulus, and B. nanus. He also speaks of five more 
species, respecting the classification of which he is less certain. 
XLVIII. Achatina. An oval or oblong univalve : the opening 
entire, and longer than wide ; the columella smooth, and truncated 
at its base. 
Bulla achatina , Linn. List. Tab. 5 I /Q, Fig. 34, is of this genus ; no 
species of which is known fossil. 
XLIX. Phasianella. A solid ovate or conical univalve : the open- 
ing longitudinal, ovate, and entire ; with a sharp plain lip : the co- 
lumella smooth, with an attenuated base. 
The opening of the shells of this genus is almost the same as that 
of the shells of the preceding ; but the shells of this genus are sea- 
shells, and are not transparent, but thick. Lamarck describes two 
species of this genus, which are found among the fossil shells of 
Grignon : P. turbinoides, and P. semistriata. 
L. Lymncea. An ovato- conical, or turreted, univalve ; the aper- 
ture entire and oblong ; the right lip joined to the left, in the lower 
part rising on the columella, and showing internally an oblique fold. 
The character by which these shells may be distinguished from the 
Bulimi, is, the very oblique fold on the columella. Helix stagnalis, 
Lin. List. Tab. 123, Fig. 21, is of this genus. The fossil remains of these 
shells are very rare. Lamarck has only discovered those of one species 
in the neighbourhood of Paris, which he names Lymncea palustris. 
LI. Pyramidella. A turriculated univalve : the opening entire 
and semioval : the columella projecting, with three transverse folds, 
and perforated at its end. 
Trochus dolobratus, Lin. List. Tab. 844, Fig. J2, is of this genus ; 
no species of which have been described fossil. 
LII. Melania. A turreted univalve : the aperture entire, ovate, 
