116 



POPULAR CONCHOLOGY. 



between the head and foot an appendage proceeding from 

 the mantle ; and on each side of the foot a horizontal 

 broad wing, extending in front into a point; the single 

 gill is large, and formed of free lobes. — 21 species 

 (Recluz.) ; also fossil. 



Very pretty shells from the Torrid Zone. 



Neritopsis. Grateloup. — Shell ovate, with a very short 

 spire of three or four whorls, increasing very 

 rapidly in size ; the exterior generally rough, with 

 rows of headings ; aperture entire, orbicular ; 

 the lip thickened within, the outer edge sharp ; 

 the columella has a notch near the middle, Neritopsis 



radula. 



which distinguishes it from Natica, to which in 



other respects it is very similar. Animal^ unknown. — 



1 species ; also fossil. 



N. radula is a very pretty shell from the Pacific. 



Family 19. — XENOPHORA CEA. 



The animals have a long extended snout, long tentacula ; 

 a small foot, which may be called stalked, scarcely equal 

 to creeping. The shell is trochiform, and is remarkable 

 for having foreign bodies adhering to its spire ; the aper- 

 ture is very oblique ; the outer lip very thin and sharp ; 

 operculum oval, with radiating lines of growth. — Marine. 



Xenophora. Fisch. and 

 Waldh. (Phorus Montf.) — 

 Shell orbicular, rather coni- 

 cal; spire obtuse; edge of 

 the whorls ornamented with 

 hollow spines, or with frag- 

 ments of shells and stones ; 

 aperture depressed ; lip acute ; 



Xcnophoj-a agglutinans. 



