94 GASTEROPODA. CARYCHIADA. 
is longest; the left tooth is thicker than any of the others. 
Peritreme very pale rose colour, or whitish. 
Vertigo vulgaris occurs in great plenty on the banks of the 
Thames, between Battersea and Eton, amongst the floating 
vegetable rejectamenta of the river ; and in marshes near Bath 
and Kingsbridge. Height half an inch. 
3. VERTIGO HETEROSTROPHA. 
V. testa sinistrorsa. 
Vertigo pusilla, Miller, Verm. 320. 
Turbo Vertigo, Mont. Test. Brit. 363. t. 12. fig. 6; M. & 
R. Trans. inn. Soc. viii. 183; Turt. Conch. Dict. 226 ; 
Dill. Desc. Cat. 880. 
Pupa Vertigo, Drap. Hist. des Moll. 61? 
Habitat in muscis, rarissima. 
Shell reversed. 
The only specimen of this species that I have seen, is in the 
collection of my friend Mr. Stephens ; but as it is in a young 
state, I cannot describe the number and position of the lamellee 
of the aperture. 
Montagu describes the shell as having “‘ three white teeth ; 
two on the Columella, and one on the exterior lip opposite.”’ 
I have quoted Draparnaud with doubt, as he has described 
the aperture to be furnished with seven folds or teeth ; “two 
on the column, two on the lateral border, and two or three on 
the opposite side.” 
It is scarcely necessary to observe, that this species differs 
from the two preceding ones, in being reversed, which is its 
constant character. 
Height one-twelfth to one-tenth of an inch. 
FAMILY III. CARYCHIAD. 
Tentacula duo, ad basin oculigera. Testa apertura plicata 
aut dentata. Umbilicus seepé clausus, in indigenis saltem per- 
foratus. 
