212 



tions, on the larger of which are often a few trans- 

 verse striae, and all of them obscurely striate lon- 

 gitudinally ; aperture narrow oval, not a third part 

 as long as the spire, with the pillar spread and white, 

 but not forming an umbilicus. 



It varies in the convexity of the volutions, and 

 their number, as we have them from different waters 

 with from six to nine. 



This animal, like the other species, but perhaps 

 more frequently, forms a thick white internal rib to 

 the outer lip, just within the edge. 



2. AMPHIPEPLEA Nilson. (Membrane Shell.) 



The animal very like Limnaus ; but the edge of 

 the mantle is much extended, so as to cover 

 (when the animal is expanded) the oval, very 

 thin, nearly membranaceous, flexible shell, 

 which, like Limnceus, has a plait on the pillar 

 lip ; its axis and part of the body whorl is 

 covered with an expansion of the inner lip. 



In Amphipeplea the same arrangement of teeth 

 prevails ; but the tubercle of the lateral teeth is even 

 still larger, in proportion to its plate. 



Miiller, Montagu, and Nilson give a good de- 

 scription of this animal. Draparnaud considered 

 the part of the mantle which is reflected over the 

 shell to be a viscid coat. 



Captain Brown, apparently not aware of the prior 

 name, has called this genus Lutea, a name that is 

 quite inadmissible. 



96. 1. AMPHIPEPLEA glutinosa. Glutinous Mem- 

 brane Shell. Shell semiglobular, extremely 



