MELO. 199 



' Melanopaia by tlie absence of the notch at the anterior part of 

 . the aperture. The Melanise occur in rivers of warm climates. 

 . The fossil species are frequent in upper mariae formations. PL 



xiv. fig. 313. 

 MELANIAISTA. Lam. (Melaniens.) A family belonging to 



the first section of the' order Trachelipoda. The genera con- 



• tained in it may be distinguished as follows. 



1. Melanopsis. Aperture notched ; columellar lip thickened 



above ; including Pirena. Fig. 315, 316. 



2. Melania. Aperture not notched ; columeUar lip not 



thickened ; including Auculosa, Pasithcsa, lo. Fig. 313, 

 314,317. ^ , 



MELANITHES. Sw. A sub-genus of Melanopsis. Sw. p. 341. 



MELAKOIDES. Olivier. Melanopsis. Eer. 



MELANOPSIS. Per. Fam. Melaniana, Lam. Entomostomata, 



• Bl. — Descr. Oval or oblong, fusiform; spire acute, sometimes 



• elongated ; aperture oblong or oval, pyriform, with a distract 

 notch at the anterior extremity ; columella tortuous, caUous, 

 thickened at the extremity near the spire ; epidermis thick, 

 horny, generally black. Subtropical. — Obs. This description in- 

 cludes the two first species of the genus Pirena, Lam. The 



' Melanopsides are known^from the Melanise by the notch in the 



aperture. M. costata. PI. xiv. fig. 315. 

 MELAS. Montf. Melania, Auct. 



MELATOMA. Sw. A sub-genus of Melanopsis. Sw. p. 341. 

 MELEAGrEINA. Lam. Magaeita. A genus composed of the 



Pearl Oyster and similar species, separated from Avicula on 



account of the roundness of their general form, but re-united 



by Sowerby. Eor generic characters, see Avicula. M. marga- 



ritifera. PL ix. fig. 164. 

 MELEAGrPIS. Montf. Turbo Pica, Auct. and similar species, 



having the aperture oblique, the columella gliding imperceptibly 



into the outer lip, and having an umbilicus. 

 MELIJSTA. Schum. Berna, Auct. 



MELO. Brod. {Melo, a melon.) Fam. Columellaria, Lam. — 

 - Descr. Light, ventricose, oval, lyith a light greenish brown epi- 



