43 
HELIX. SNAIL-SHELL ,. 
of the flattened surface of the outer volution, and some¬ 
times produced into an oblique angle at the upper and 
outer end, the margin thin, and slightly embracing the next j 
volution at the sides : diameter the tenth of an inch. , 
This new species, sufficiently distinct from anyofiudi* 
vision by the mouth, which forms an oblique parallelo¬ 
gram, resembles the H. ulbina of Gmelin, except that it is , 
nearly equally concave on both sides : we have as vet only 
found it, attached to the cases of the Phryganete, in its larva 
state, in the pond at Glasnevin botanic garden, near Dublin, | 
where they are met with in tolerable abundance. These cases 
are chiefly clothed with this shell, the H. planorbis and i 
planata; Turbo fontinalis, and the young of Tellina cor¬ 
nea. v. v. 
9. Helix contorta. Coiled Snail-shell. 
Montagu, pi. 25. f. 6— Da Costa, pi. 4. f. 11— Donovan, 
pi. 99—Dorset Cat. pi. 20. f. 11. 
Shell flat, horn-color, sometimes rufous or whitish, con¬ 
cave in the very centre only on one side, but largely and 
deeply so on the other : spires six, rounded, finely striate, 
deeply divided by the line of separation : aperture narrow 
crescent ►shaped> like the moon in its first quarter, pointed i 
at the sides: diameter hardly two tenths of an inch. 
It differs from H. spirorbis, in the deep cavity on one 
side, the narrow aperture, and the number and compactness 
of the volutions. 
Ponds and wet ditches, v . v. 
10. Helix alba. JVhlte Snail-shell. 
Montagu , pi. 25. f. 7— Dorset Cat. pi. 19. f. 18— JFatter, 
f. 19. 
Shell flattish, pale horn-color, semitransparent, often co¬ 
vered with a brown skin, slightly concave on one side and 
more deeply so on the other : spires four, finely rounded, 
very closely blit distinctly striate both across and circu¬ 
larly ; the larger volution very faintly inclining to an edge 
or keel: aperture somewhat orbicular or crescent-shaped, 
a little oblique and clasping the spire : diameter a quarter 
of an inch. 
‘ Ponds and slow streams, v. v. 
> '11. Helix 
