24 



FKLSn-WATEK SHELLS. 



hence, perhaps, the scientific name applied to the family in 

 which they are mostly included — Limnaidce, which, like limn — 

 to paint, agrees with the French enluminer. These molhisks 

 are found in rivers, streams, ditches, and moist marshy places. 

 Like tliose which live wholly on land, thej- breathe through 

 lungs, and therefore cannot exist without air; which accounts 

 for their frec^uently coming to the surface, when under water. 

 In brooks, as well as in stagnant pools, which abound with 

 aquatic plants, they may be found in vast numbers, feeding 

 upon the moist vegetation. 



The Common Limnea, fL. stagnah'sj is mostly an inliabitant 

 of stagnant waters, where it is often seen floating with the 

 shell reversed, as in a boat; this shell, like most of those 

 of the Fresh- water Mollusks, is thin, and easily broken; the 

 shape it will be seen, is ptx'uliarly elegant, the spire being 

 slender and pointed — very different from that of the Spreading 

 Limnea, called by naturalists, L. aKrieularia, from auruH — 

 the ear, to which the broad aperture, or opening of the shell, 

 may be compared; this resembles the other species in its liabits. 



The Horny Planorbis, in Latin 

 P. corneus, from eornu — a horn. 

 The shape, you will see, is flat, 

 the whorls rolling upon each 

 other like the folds of a bugle 

 horn ; this shape would be termed 

 orbicular, from orlis — a si)here, 

 or circular body. This is the 

 largest European species of Fresh- 

 water Shells so constructed ; it is 



