Shells of Common Occurrence. 139 
mucous thread to descend. The spotted grey slug 
(L. cinereus), best known as the black slug, but 
not to be confounded with the Arion, though less 
common than the field slug, is very abundant in 
damp situations, under decaying wood and frag- 
ments of stones in gardens, hedges, etc., and in 
cellars and outhouses; copious rain, or even dew, 
enticing it from its retreat. It is the largest of 
the slug family, being six inches long, and will 
be found handsomely formed when attentively 
surveyed. It is circular on the back, acute and 
pointed at the tail; with upper tentacles of great 
length and short lower ones; it secretes colourless 
mucus. ‘The shield is slightly stained with pink. 
It deposits during spring from fifty to sixty eggs, 
attached in heaps together, under stones and at 
the roots of grass and trunks of trees. 
The Helix, or snail, has a shell spirally rolled, 
and although possessing no operculum, it sub- 
stitutes that filmy mucous covering, by means of 
which it closes up its shell, and which is perforated 
with holes to enable it to breathe. Remaining 
concealed in obscurity during the day, it comes 
forth to feed evening and morning, or after rain, 
retiring from business altogether in the winter into 
a hole or crevice, or amongst moss, and shutting 
