138 LIMACIDJE. 



which is iridescent when dried. Its eggs are deposited 

 in a cluster and slightly attached to each other. When 

 alarmed, or at rest, this slug merely draws its head within 

 the shield, but does not otherwise contract its body. 

 When irritated, it is said to expand its shield. It is 

 liable to be infested, as well as some of the other slugs, 

 by a white parasitic mite, called Philodromus (or Acarus) 

 limacum, which swarms about its body and, according 

 to Mr. Jenyns, dwells in its respiratory cavity, but which 

 does not seem to cause the slug any harm or incon- 

 venience, except perhaps in feeding on its slime and 

 slightly lessening the secretion. Mr. Daniel informs me 

 that these slugs suspend themselves in pairs during the 

 breeding-season by threads of slime, and that they always 

 feed by night, but that the variety cinereo-niger of 

 Mlsson prefers terra firma to mid-air and keeps much 

 more respectable hours. Like all other slugs and snails, 

 it will soon eat its way out of a large pill-box, or even a 

 stouter one made of cardboard, if confined in it. The 

 shell or ossicle which is contained under the shield was 

 known to Pliny ; and it was used by the ancient phy- 

 sicians for the sake of its carbonate of lime. The sub- 

 stratum of this shell is membranous ; and a layer of the 

 same filmy material covers the upper surface, having the 

 appearance and character rather of a periosteum than of 

 a Molluscan epidermis. 



The young of this species may be distinguished from 

 L. arborum, among other respects, by its upper tentacles 

 being proportionally much longer, as well as by the pos- 

 terior margin of its shell being more pointed. The shell 

 of L. maximus is also longer, more convex, and thicker. 



Miiller gave this species the name of cinereus, on the 

 supposition that the L. maximus of Linne* might be a 

 variety of Arion ater ; but the diagnosis of the great 



