LIMACID^. 75 



ribbed ; lingual ribbo7t with numerous transverse rows of 

 spinous teeth. 



Shell rudimentary, consisting of calcareous granules, or shield- 

 like ; in either case covered by the mantle. 



This family comprises those molluscs popularly- 

 known as Slugs, whose bodies are unprovided with an 

 external shell, though the vital parts are protected 

 by a more or less rudimentary testaceous covering 

 placed beneath the mantle. The slugs exude an 

 abundance of slime which serves to lubricate the skin ; 

 it is very tenacious and capable of being drawn out 

 into a thread by which the animal is enabled to sus- 

 pend itself from the branches of trees, or descend in 

 safety from a considerable height to the ground. 

 Most of the slugs, especially when young, seem to 

 possess the faculty of thread-spinning. In his paper 

 on ' MoUuscan Threads,' from which an extract has" 

 already been made,* Mr. Sherriff Tye writes as fol- 

 lows : — " Mr. Wm. Harte (in ' Proceedings Dublin 

 N. H. Soc.,' vol. iv. part ii.) has recorded some inter- 

 esting experiments he made with Limax arborum, 

 causing it to spin a thread and to reascend by it, and 

 he believes that from the ' perfect ease and regularity 

 with which they do it, that they are well accus- 

 tomed to it' Mr. Harte also states that if the slug 

 be ' gorged with food ' the slime is thin and not so 

 able to sustain it, but if kept overnight without food 

 it performs well the next morning." 



The Limacidse are extremely voracious ; their food 

 chiefly consists of vegetable matter, but many of them 

 devour animal matter also. A popular and very 



* Vide p. 52. 



