136 LIMACID^E. 



shield rounded in front and obtusely angulated behind, the 

 concentric or transverse striae rather fine, streaked length- 

 wise, the middle stripe being usually darker : tentacles short, 

 yellowish-grey : back distinctly keeled towards the tail : foot 

 having its edges nearly white : slime colourless. L. 3. B. O4. 



SHELL squarish-oval, nearly flat, very thin, glossy, and 

 iridescent, with minute nacreous tubercles ; lines of growth 

 indistinct, obliquely striate as in the last species : boss 

 nearly inconspicuous and subterminal : margin broad, thin 

 and membranous. L. 0'2. B. 0'125. 



HABITAT : Trees (especially the beech), as well as among 

 rocks and under stones, both inland and on the sea-coast, 

 in most parts of Great Britain, from the north of Zetland 

 to the Channel Isles. According to Von Martens, it is 

 the L. Livonicus of Schrenck, and inhabits Russia ; it 

 occurs in several parts of Norway ; Bouchard-Chan- 

 tereaux and Normand have instanced localities in the 

 North of France, and I have found it in the Lower Harz : 

 but it has not been noticed further south. It has been 

 probably mistaken for the young of the next species. 



M. Bouchard-Chantereaux, who first described the 

 tree-slug, says that it prefers old trees, feeding on de- 

 cayed wood and not touching the leaves ; and he adds 

 that it is not prolific. He has often seen the young 

 (which he believes to be the L. filans or spinning-slug of 

 Hoy and some other English authors of the last century) 

 spin its slimy thread and descend from one branch to 

 another, but not plunging into air (or taking what bathers 

 would call " a header ") without apparent fear and 

 hesitation, the sole of its foot exhibiting during the 

 descent a similar movement to that which is observable 

 while it is crawling on the sides of a glass vessel. In a 

 remote cluster of the Shetland Isles, called the Out- 

 Skerries, where I have taken this slug, with my friend 

 Mr. Norman, no trees exist ; but perhaps it found de- 



