SLUGS. 97 
farther into the shell, after the formation of the 
operculum, is again inspired, and each separate 
membranous position broken by the pressure of the 
hinder parts of the foot, projected through the 
mantle. When it arrives at the calcareous oper- 
culum, the animal, making a last effort, bursts and 
detaches its most obtuse angle; then, insinuating 
by littleand little the edge of the foot between the 
shell and the operculum, it forces the latter off, or 
breaks it away.’’* 
Famity LImMAcIDé. 
(Slugs. ) 
In general, the animals of this family resemble 
those of the preceding. The body, however, is 
lengthened and slender, attached to the foot by its 
whole length, instead of rising into a spire. The 
mantle is generally small, not nearly covering the 
body. ‘The shell is minute and rudimentary, some- 
times concealed within the substance of the mantle, 
and sometimes altogether wanting. 
In general the Slugs are, like the Snails, herbi- 
vorous ; but the curious genus Testacella, of which 
a species has been found in the neighbourhood of 
London, feeds almost exclusively on earth-worms. 
GENUS LIMAX. 
Our common Slugs, but too familiarly known, 
have a lengthened body, with a granular surface, 
keeled behind. The mantle is small, covering like 
a shield the fore part of the body. Its substance 
encloses a small, flat, transparent, oval shell, some- 
what resembling the human nail. 
* Zool. Journ. i. 
H 
