Skeneidae 133 



faintly yellowish with thin epidermis; apex acute, nuclear whorls 

 smooth; six or seven convex whorls; sutures shallow; 16 to 20 

 strong axial ribs; equal, smooth interspaces; aperture oval, entire; 

 outer lip thick, a little flaring; operculum corneous, pale brown, 

 having an internal apophysis which articulates with columellar 

 lip. 



Abundant on grassy bottoms in shallow water. Often found 

 on eel grass. 

 Bissoina laevig'ata237 (c. B. Adams) PI. 48, fig. 332 



Alt., 4 mm. Shell fusiform, small, smooth, glossy, pellucid 

 white, sometimes with opaque spots; thin, transparent epidermis; 

 apex small, prominent; nine or ten slightly convex whorls; sutures 

 shallow, incised, with opaque borders; aperture oval, entire; outer 

 lip thick, a little flaring; operculum corneous, light-amber color. 



Less common than R. hryerea. Found on grassy bottom beyond 

 littoral zone. 



Family SKENEIDAE 



The Skeneidae is a family of small moUusks including genera 

 distributed from Greenland to Florida and the West Indies. 



Genus ADEORBIS Wood, 1842 

 Adeorbis b«aui-38 p. Mscher PI. 25, figs. 178a, b 



Alt., 4.75; extreme diameter of base, 11.5 mm. Shell rather 

 thick, pure white, flattened, almost discoid; about three whorls; 

 sutures channeled, body whorl sharply keeled at periphery and base; 

 spiral sculpture of five, nearly equidistant strong ribs, with fine 

 threadlike ribbing in interspaces. Between suture and uppermost 

 strong rib is a broader band of fine ribbing; between peripheral and 

 basal ribs, the surface is smooth, showing only lines of growth; aper- 

 ture rounded, entire; base with delicate spiral and growth lines; 

 deep, funnel-shaped umbilicus open to apex; operculum corneous, 

 light brown. 



Occasionally found on beaches. Dredged in three fathoms. 



237 Lat., laevigatus, made smooth. 



238 Lat., ad, to, toward; orbis, circle; dedicated to M. Beau, friend of P 



Fischer. 



