164 INTEODUCTION TO CONCHOLOGY. 



preserved from extinction during tlie lieat of summer ; and, 

 when no longer surrounded by their native element, they 

 await without inconvenience the overflowing of their arid 

 dwelling-places. 



This peculiarity of character was first made known by 

 Guildiug, in his ^Zoology of the Caribbean Islands/ and 

 has since been confirmed by some specimens of Amjoullance 

 brought by ]\I. CailHaud from Africa. 



Pamily XII. Melaniana. 



Those wlio go forth to gather shells by streams. 

 Or mountain torrents, or still inland lakes. 

 Find but scant beauty in their dingy forms ; 

 Yet each, methinks, doth fitly fill some space, 

 And hath its own small sphere of quiet duty. 



Sliell turriculated ; columella sometimes thickened at the 

 upper part ; aperture entire or emarginated, margins dis- 

 joined. Animal strictly fluviatile, and furnished with a 

 horny operculum. Two genera belong to this family. 



The genns Melania is found located in lakes, rivers, and 

 rapid streams, which often sweep onward, with their breadth 

 of waters, through deep and primeval forests. Their shells 

 exhibit little of external beauty, and are, for the most part. 



