PART II. MELANIAN.fi. 341 



Melacantha Sw. Spire and aperture 

 nearly of equal length ; the whorls 

 coronated with spines; inner lip 

 very thin. 

 M. amarula Sie. Zool. 111. ii. pi. 29. 



f. 1. (fig. 102. a.) 

 setosa Sw. Ib. ii. f. 2. 



Melania Lam. Subulate and elon- 102 



gated; inner lip wanting, (fig. 102. 6.) 



M. quadriseriata. Griff. Cuv. 14. f. 3. 



Potadoma Sw.* General characters of Melania; but the 

 outer lip is hardly dilated, and the top of the inner 

 lip is internally thickened. 

 P. Frethii. Griff. Cuv. 14. f. 2. laevis. Ib. 14 f. 8. 



Hemisinus Sw. General shape of Melania ; but the 

 base of the aperture is contracted and emarginate ; 

 outer lip crenated. 



H. lineolata. Griff. Cuv. xii. pi. 13. f. 4. 



Melanella Sw Obovate ; spire scarcely longer than 

 the aperture, which is entire ; inner J ; p much thick- 

 ened its whole extent, t 



MELANOPSIS Lam. General form of Melania; but the 

 spire shorter, and the base of the aperture notched. 



Melafusus Sw. Sub-fusiform; the base contracted, 

 and the aperture and spire nearly equal. 

 1 Species, America. 



Melanopsis Lam. Obovate ; the base obtuse ; 

 spire pointed, acute ; inner lip greatly thick- 

 ened, particularly at its upper part, and in- 

 ternally ; suture compressed and flattened, 

 buccinoides Lam. (fig. 103.) 



Melanithes Sw. Habit of Melania ; but the spire is 

 obtuse, and the suture prominent. 

 Fe'rus. Moll. Melanop. pi. 2. f. 1 1, 12, 13., pi. 1. f. 5. 7. 16. 



* I suspect that the true distinction of this second type of Melania will 

 rest on the deciduous nature of the spire. 



t This type, which represents Planaxis,' unites on the other side to Me- 

 lacantha. I have a small species, but know not whether it is described.. 



z 3 



