LAND SNAILS. 
107 
high; diameter one-fifth to a quarter of an inch. 
The dental formula is 
Helicella nitidula — (the Dull Snail) (PI. 
VII., fig. 60)—is generally distributed, but not 
a very common shell. Under stones, about old 
walls, among mosses in glens and sheltered 
places. 
The shell is flattened, with the spire somewhat 
raised (more so than either of the preceding); 
colour that of horn, not shining, and darker than 
that of H. cellaria or H. alliaria , dull, semi¬ 
transparent above, more transparent below, ex¬ 
cept about the umbilicus, where there is a slight 
white opacity; upper surface irregularly wrinkled 
or striated; the striae interrupted by the sutures, 
and not continued from whorl to whorl, as in 
H. radiatula; whorls four and a half, with a 
well-defined suture; umbilicus large, exposing 
the previous whorl; aperture crescent-shaped, a 
little oblique, rather broader than high; dia¬ 
meter three-eighths to three-tenths of an inch. 
The dental formula is - 2 5 ^ 32 -. 
Helicella pura — (the Delicate Snail) (PI. VII., 
fig. 55)—is not uncommon among moss, decay¬ 
ing leaves, stumps of trees, and under stones in 
woods and pastures. 
The shell is flattened, with the spire very slightly 
raised; colour white, rarely very pale amber; 
transparent, not very shining; under surface 
