18 LIMACID^. 



a light central stripe, at first sight resembliug a keel. 

 The dark markings sometimes form two stripes, or two 

 rows of blotches on each side. The sides of the foot 

 are pale, sometimes nearly white ; the sole is white. 

 The mucus is quite colourless. The shell varies much, 

 some examples being thick, others thin ; it is Avhite, 

 pearly, irregular, slightly convex above, and concave 

 below, with straightish sides, and a not much arcuated 

 base. The eggs are oval, and are laid separately. The 

 tree-slug grows to a length of rather less than three 

 inches. It lives on trees, especially old and decaying 

 ones, eating the wood. It may be found on the ground 

 under fallen trunks, and loose stones in the immediate 

 neighbourhood of trees. Young individuals let them- 

 selves down from branches by threads of mucus, and 

 in that condition, probably constituted, as has been sug- 

 gested by M. Bouchard, the Limax filcms of Hoy, Shaw, 

 and Latham. The tree-slug has been overlooked on the 

 British trees, until attention was called to it in the ex- 

 cellent memoir of Irish Limaces by the Rev. B. J. Clarke, 

 who found it widely distributed in Ireland, almost always 

 on trees. According to Mr. Thompson of Belfast, it is 

 common in the north of Ireland. We have found it 

 of a large size near Cork. 



In Scotland it appears to be the slug from Aber- 

 deen described, by Professor Macgillivray, as the mar- 

 ginatus of Midler. Mr. W. Thompson has found it in 

 Islay. 



In England, Mr. W. Backhouse, and Mr. H. Embleton 

 communicated it to Mr. Alder, from localities in Northum- 

 berland. Mr. Byevly finds it abundant on trees in the 

 neighbourhood of Liverpool. Mr. W. Thompson has 

 met with it in the Isle of Wight, and we have found it 



