26 LIMACID^. 



mycus, and we accordingly described it as such. Hav- 

 ing an opportunity since that time of examining several 

 of them, we noticed, on throwing some of them into 

 alcohol for preservation, that the contraction, caused by 

 the hquor, revealed and detached the mantle from its 

 adhesion. Its characters, therefore, correspond with 

 those of the present genus. It is by no means certain, 

 however, that it may not pBove to be the young of the 

 precedmg species. 



Genus ARION, Ferussac. 



Generic Chaeacteks. Posterior termination of body 

 obtuse. Integuments crowded with elongated tuberos- 

 ities on the back, and on the sides with elongated tuber- 

 cular plates having furrows between. Mantle anterior, 

 oval, small, covered with granulations, free at the front 

 and on the sides, attached posteriorly, containing in its 

 posterior part numerous fine calcareous sandy grains. 

 Locomotive disk not expanded at the margin, when the 

 animal is fully extended very narrow, having in some 

 species a naiTow median band, and in others not. Re- 

 spiratory orifice at the anterior margin of the mantle, 

 small. Anal orifice contiguous to the former. Orifice of 

 organs of generation under the two last. On the upper 

 part of the posterior extremity of the body is a triangular 

 pore or sinus, with the point directed forwards, a process 

 or projection of the integument serving as a cover to the 

 sinus. 



