336 



HELICID^. 



ish, but within it is brownish, and often thickened. The 

 indentation of the last -whorl, terminating at the angle of 

 the lip, is a prominent character. The teeth of the lip 

 are often curved towards the centre of the aperture. 



The motion of the animal, when in progress, is 

 rapid, but awkward. The proboscis, which is long and 

 projectile, seems to be thrust forward, and attached, 

 and the rest of the foot drawn up to it, reminding one of 

 the motion of a caterpillar, the shell at the same time 

 rolling from side to side. The adherent forces of the 

 animal evidently lie in the anterior part of the foot. 



This is one of the more aquatic species, and is found 

 under dead leaves and sticks, and on the stems of plants, 

 at the margin of rivulets and ponds. 



An opportunity for examining the original specimen 

 of Mr. Say's P. modesta having been aiforded, it proves 

 to be this shell, with the aperture somewhat modified by 

 its having been fractured. 



