14 BRITISH MOLLUSKS. 



Professor Allman, to whom we are indebted for the first descrip- 

 tion of Geomalax, remarks that the habits of this mollusk are some- 

 what curious. "It possesses a singular power of elongating itself, so 

 as at times to assume the appearance of a worm. By this means it 

 can insinuate itself into apertures which we coidd scarcely conceive 

 it possible to enter. This curious property indeed was very nearly 

 the cause of my losing the first, and only specimen I had seen. I 

 had placed the mollusk as I supposed securely in a botanical collect- 

 ing box, when to my surprise, I found shortly after, that it had 

 transgressed the limits I had assigned it. The creature not liking 

 its confinement, had insinuated itself beneath the lid." 



G-entts III. UMAX, Linncens. 



Animal ; body cyHndrically elongated, more or less tapering, 

 rounded on the back, sometimes keeled throughout, sometimes 

 keeled only towards the tail, integuments variously wrinkled, 

 furrowed, and veined; head with two pairs of tentacles, of 

 which the upper pair is much the longer, bearing minute eyes 

 at their bulbous extremity ; shield sometimes finely granulated, 

 sometimes concentrically striately wrinkled, enclosing a rudi- 

 mentary shell, respiratory orifice at the right margin, more or 

 less posterior to the centre. 

 Shell ; an oval agglomerate, or a symmetrically-developed valve, 

 increasing in concentric order from an umbonal nucleus, covered 

 by a thin membranaceous epidermis. 

 The slugs of the Limax type differ from those of Arion, in having 

 the pulmonary sac situated rather more removed from the head, 

 with the respiratory orifice behind, instead of being in front, of the 

 centre of the right margin of the shield ; and sometimes it is quite at 

 the posterior extremity. Among other generic differences it may be 

 noted that the body of the creature is always more cylindrical and 

 tapering, it is always more or less keeled, and the rudimentary 

 agglomerate of calcareous particles assumes the form of an oval 

 plate passing into an oblong square shell, developed in regular con- 

 centric order from an umbonal nucleus, and covered by a membra- 

 naceous epidermis. In colour the Limax is as inconstant as the 

 Avion, and presents greater variety of marking. 



We have eight species of Limax recorded as British, but two of 



