Shells of Common Occurrence. 137 
mucilaginous matter, animal and vegetable, slugs, 
when boiled, have been employed as a cure for 
consumption. When hard pressed by hunger only 
will they eat dead earth-worms, and hence their 
blight falls chiefly on the growing plant. The 
observer may occasionally have felt startled to sce 
the [imax suspended by an almost invisible but 
very tenacious thread which it possesses the power 
of spinning, betwixt him and the lght. This is 

1. Limax agrestis (the Milky Slug), Miller. 2. L. flavus 
(the Yellow Slug), Iinneus. 3. L. arborum (the Tree 
Slug), Chautereaus. 4, L. cinereus (the Spotted Slug), 
Miller. 
used by the slug to drop from on high. Like the 
spider, it exudes this mucous thread from the 
secretions of its body. Encumbered with no 
mansion which it must carry on its back like the 
snail (Helix), the slug is yet more hardy without 
its shelter than the Helix, and remains active far 
into the winter, when the other lies dormant in the 
crevice of the wall. 
The most common slug of the fields, L. agrestis, 
or milky slug, about an inch and a half long, is the 
