PART II. 



MELANIANiE. 



341 



Melacantha Sw. Spire and aperture 



nearly of equal length ; the whorls 



coronated with spines ; inner lip 



very thin. 



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

 f. 1. {fig. 102. «.) 

 setosa Sw. lb. ii. f. 2. 



Melania Lam. Subulate and elon- 

 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. l^vis. lb. 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 ,''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 ; io3 A 

 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. 

 Ferus. 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 oi Melania will 

 rest on tlie deciduous nature of the spire. 



+ 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 



