190 LAND AND FRESH-WATER MOLLUSKS. 
Limn^a auricularia —(the Wide-mouthed or 
Ear-shaped Mud Shell) (Pl. X., fig. 119).—A 
large shell,, and, without doubt,, one of the most 
beautiful of the genus, remarkable for its globose 
form, and vastly expanded and roundish oval 
aperture; the spire is very short and acute; these 
characters serve to distinguish it from L . peregra. 
The shell is moreover beautifully glossy and 
semi-transparent; the lines of growth are deep 
and irregular. When the shell has lain dead for 
some time in the water, it becomes opaque, pale 
yellow externally and white within. 
It has the habits of, but is less active than, the 
former species. It is local and rare; usually 
frequenting slow rivers, canals, and deep ditches; 
it is not uncommon in the valley of the Thames, 
and in low districts of the Eastern Counties; it 
has not been observed in Scotland. 
Limnjja staonalis —(the Lake Mud Shell) (PI. 
X.., fig. 114).—The shell of this species is larger 
and longer than that of any other Limncea , being 
an inch and a-half long and nearly an inch wide; 
it is thin, brittle, of a greyish-white, brown or 
red colour; the spire is composed of six or seven 
rounded whorls, the last one occupying nearly 
three-fourths of the length of the shell. The 
shell varies in thickness, according to the nature 
of the water and food; in ponds, the last whorl 
is often much inflated; in clear running water, 
