SHELLS OF COMMON OCCURRENCE. 



BY WILLIAM WALLACE FYFB. 



The Limacidce, or land-slugs, are represented con- 

 chologically by the thin crustaceous shells found on 

 dissection within their mantles, being, as every- 

 body familiarly knows, outwardly destitute of shell. 

 This shield is protective of the cavity employed in 

 respiration. Pigs. 1, 2, 3, and 4 represent four of 

 these shields, extracted from the milky, yellow, 

 tree, and spotted slugs respectively (Limax agrestis, 

 L. flavus, L. arborum, L. cinereus). 



These creatures, as every lover of a garden too 

 well knows, are powerful vegetable feeders, making 

 their appearance in damp weather in multitudes 

 like an Egyptian plague. Their destructive voracity 

 enables them to secrete an exuberance of white 

 milky mucilage from their bodies, to discharge this 

 copiously when irritated, and to mark their devour- 

 ing tracks in their slime. Like linseed and other 



