2i2 Bidletin Amerionn Maiscim of Natural History [Vol. LIII 
The mutans blend is more abundant in this station than in any 
other. | 
Moanda, from the mangrove swamps just below the mission, on the 
river. The form fusca is only rarely developed typically, and is always 
preceded by a long granulosa stage; generally the keels are relatively 
weak, or the lower one wanting. | ! 
Landana (Pl. XXIV, fig.6). Only the form granulosa, specimens with 
numerous small axial ribs. 
Fig. 45. a, teeth of Potadoma ponthiervillensis mut. spoliata (Putzeys), an outer 
marginal lying prone at left. 6, operculum of Potadoma liricincta walikalensis Pils- 
bry and Bequaert. 
_ a, anterior margin, and b, posterior margin of basal plate; e, embayment line; p, platform line; 
r, rise line. 
Potadominse 
PoTapoMaA Swainson 
Melania subgenus Potadoma SWAINSON, 1840, ‘Treatise on Malacology,’ pp. 200 
and 341. Includes two species: M. freethii Gray and M. levis Gray. 
Melania subgenus Nigritella Brot, 1870, American Journ. Conchol., NAY 2: 
Appendix, p. 277, for several species, among them M. nigritina Morelet, but no type 
designated; 1874, in Martini and Chemnitz, ‘Syst. Conch. Cab., I, 24, Melaniaceen,’ 
p. 6, with M. nigritina Morelet designated as type. Not Nigritella E. v. Martens, 
1860. 
Melania section Nigriculina RovERETO, 1899, Atti Soc. Ligustica Se. Nat., X, 
p- 109. Substitute for Nigritella Brot, 1870. 7 
Type: Melania freethii Gray, as designated by Hermannsen, 1847, ‘Ind. Gen. 
Malac.,’ IT, p. 329, and also by Gray, 1847, Proc: Zool. Soc. London, p. 152. Accord- 
ing to Brot, 1874, in Martini and Chemnitz, ‘Syst. Conch. Cab., I, 24, Melaniaceen,’ 
[p. 487], the British Museum specimen of M. freethit Gray, from Gray’s collection, 
does not differ from M. nigritina Morelet, and E. A. Smith, 1887, Proc.*Zool. Soe. 
London, p. 566, also admits that they are the same. 
