144 TESTACELLID^E. 



mistaken in supposing that the whole of the body was 

 enveloped by the mantle. If this slimy pellicle be sud- 

 denly removed, the Snail-slug is liable to be attacked by 

 a disease which usually ends in its death. Heavy rains 

 destroy a number of them. The average length of life in 

 the TestacellcB appears to be five or six years. Their 

 smell is like that of worms, but even more nauseous. 

 They chiefly frequent gardens, where they are sure of 

 finding their proper food ; but they may occasionally be 

 met with in woods near inhabited places as well as at the 

 foot of old walls. In winter they bury themselves very 

 deep in the ground ; and my gardener once brought me 

 living specimens of T. Mangel which he had dug up in 

 trenching some celery-roots at a depth of about two feet. 

 The eggs are laid separately, and are very large in pro- 

 portion to the size of the body. These somewhat re- 

 semble hen's eggs both in shape and consistency, and 

 are covered with a rather thick and tough skin. If they 

 are taken out of the earth and exposed to a cold air, they 

 frequently crack and burst in pieces which fly off to some 

 little distance. Faure-Biguet appears to have succeeded 

 in preserving the eggs under such circumstances by 

 plunging them as soon as taken into boiling water. It 

 is believed that the Testacellce never come to the surface, 

 except occasionally during the breeding-season, but that 

 at all other times they live underground. Their eyes, 

 however, are perfect ; and their horns, or tentacles, are 

 rather long and extremely sensitive. 



