FAMILY 1. MELANIANA. 121 
The shell of the Melaniana may be described as being turriculated, with 
the columella sometimes thickened at the upper part; the aperture is 
either entire or emarginated, and the margins are disjoined. The animal 
is strictly fluviatile, and furnished with a horny operculum. 
We refer the following two genera to this family : 
MEtania. MELANOPSIS. 
MELANIA, Lamarck. 
Testa turrita, vel subturrita, externé szepissime rugifera, aut nodulosa, epi- 
dermide fusco-nigra plerumque induta; spira interdum brevissima, 
apice sapé valdé eroso; columella levi, incurva; apertura integra, 
vel ovata, vel oblongo-ovata, supra acuta, infra canali indistincto in- 
terdum sinuata, labro simplici, acutiusculo. Operculum corneum, 
spirale. 
The genus Melania was founded by Lamarck for the reception of a 
group of freshwater Pectinibranchiata, which have a dark solid turricu- 
lated shell, somewhat like that of the marine Cerithia, arranged by Lin- 
neeus with the Helices, and by Bruguiére with the Bulimi. They differ essen- 
tially from the Lymnee, inasmuch as they breathe only in water: their 
places of habitation are also distinct ; the Lymnee@ inhabit fens, ditches 
and shallow pools, but the Melaniz are found located in rivers, lakes and 
rapid streams ; their shells, which are altogether more solid and calca- 
reous, exhibit for the most part that dark dingy colour which more or 
less characterizes the shells of all fluviatile mollusks, and, like the rest of 
them, are generally more or less eroded. Some that have been referred 
to this genus by authors, must, however, be removed, if only on account 
of their being marine; the Melania nitida, for example, which has been 
selected for the formation of the genus Eulima, and the Melania cochlea- 
rella for the genus Rissoa. The many varieties of Melanie that have 
been discovered in the great rivers of America have induced the concho- 
VOL. II. R 
