110 Marine Shells of the Western Coast of Florida 



Family VITRI>ELLIDAEi89 



The shells of this family are white or corneous, sometimes 

 transparent, with no trace of a nacreous layer; their form is turbi- 

 nate, depressed, deeply umbilicate, with an almost circular aperture 

 and simple, sharp lip. The operculum is corneous, similar to the 

 trochid operculum. 



Genus PARVITURBOIDES Pilsbry and McGinty, 1950 

 rarviturboidesi"" iiiterriiptuni saiiibelense Pilsbry PI. 22, figs. 141a, b 



Alt., 1.1 mm., diam, .9 mm. Shell is low-turbinate, base flat- 

 tened and somewhat funnel-like around the narrow umbilicus; color 

 slightly off white, moderately translucent; thin, papery periostra- 

 cum; about three and a half rounded whorls; upper whorls almost 

 smooth; spiral threads with wider interspaces, begin on penultimate 

 whorl, increasing in number to seven on body whorl; the interspaces 

 are crossed by occasional faint growth lines. The aperture is simple, 

 oblique and a little flattened above; outer lip thin; columella a little 

 thickened with a short parietal callus below. The operculum is cor- 

 neous, multispiral, much resembling the operculum of Calliostoma. 



Genus CYCLOSTREMISCUS Pilsbry and Olsson, 1945 



Cyclostremiscus"! (?) trilixi^^ (Bush) PI. 22, figs. 142a, b 



PI. 49, figs. 336a, b, c 



Alt., 1 mm., diam., 2.3 mm. Shell white with thin perio- 

 stracum; turbinate, much depressed, apex slightly elevated; two or 

 three whorls, evenly convex at shoulder, flattened above and below, 

 sutures not channeled; aperture rounded, simple, oblique in outline 

 and oblique in relation to vertical axis of shell; outer lip thin; 

 whorls are almost destitute of sculpture, a few lightly incised 

 spirals and often a slight puckering below sutures; base shows one 

 well-mcised spiral near outer margin and one or two others less 

 defined; umbilicus deep and funnel-shaped, showing turn of whorls to 

 apex. 



Dredged in four fathoms. Gulf of Mexico off Sanibel Island. 

 Occasional beach specimens. 



^**'' Lat., 'vitruin, glass; shells of glassy texture. 



'"''Lat., parvus, little; turbo, top, circle; Gr., eidos, form, shape. 



'•'1 Gr., kykyos, circle; trema, aperture. 



^''-Lat., trt, three; lixa, flowing (lines). 



