300 



SHELLS AND SHELL-FISH. 



truncated; spire very short; both lips thickened, 

 the inner granulated, the outer inflected and toothed ; 

 aperture narrow, {fig. QQ. c.) 

 oniscus. Chem. 1872-3. cancellata. Sow. Gen. f. 1 — 3. 



Vexilla Sw. General shape of 

 Purpura ; the inner lip flat- 

 tened and depressed; the outer, 

 when adult, thickened, in- 

 flected, and toothed ; aperture 

 wide. 



picta Sw. Chem. pi. 157. f. 1504-5. (fig. 67.) 



Nassa Lam. Small ; spire longer than the 

 aperture ; the inner lip, in the typical 

 forms, greatly dilated, thickened, and often 

 with a prominent margin ; outer lip simple, 

 crenated; aperture wide, with a groove above ; 

 pillar with a basal ridge ; base truncate, {fig. 68.) 

 N. arcularia. Ency. M. 394. f. 1. clathrata. lb. f. 4. 

 papillosa. Sow. Gen. f. 5. 



Cyclonassa* Sw. Shell small, depressed, neritiform, 

 nearly round ; inner lip forming a vitreous, spreading 

 mass ; no internal canal or tubercle on the inner 

 lip ; basal notch nearly obsolete ; outer lip smooth, 

 entire, thickened. 



C. neritea. Ency. M. 394. f. 9. Sow. Gen. f. 3. 



SuB-FAM. 4. PURPURIN^. 

 Oval; spire much shorter than the aperture, which is very 

 wide ; inner lip not defined, but vitreous ; pillar broad 

 and flattened ; outer lip rarely thickened or inflexed. 



RiciNULA Lam. (fig. 71. d.) Outer lip dilated, and often 

 forming digitated processes externally, but the margin 

 broad, much reflected, and toothed internally ; inner 

 lip flat, broad, generally toothed ; spire very small, f 



planospira. En. M. 397.5. digitata. Sow. Gen. f. 3, 4. 



horrida. Sow. Gen. f. 1. morus. lb. f. 2. 



* ThefaHciful and inapplicable name of Cyclops, given to this type by 

 De Montford, designates a well-known genus of Crustacea, 

 f Except in those species, like R. morus, which lead to Purpura. 



