1818.) GENUS OLYGYRA. 283 



Genus ^OLYGYRA. 



Shell round-d; aperture longer than broad, semior- 

 bicular, einarginated by the projection of the penuhimate 

 whorl; external lip reflected; pillar lip with obsolete cal- 

 careous deposit; umbilicus none; columella slightly an- 

 guiateci at base. 



Animal ta:vcs\xi'A, operculated; tentacula two, filiform; 

 eyes prominent, placed at the external base of the tenta- 

 cula; rostrum bilabiated at tip, shorter than the tentacu- 

 la; ybo^ simple. 



SPECIES. 



O. ^orhiculata. Shell subglobular; spire not promi- 

 nent, but more than convex; lateral line somewhat con- 

 vex; whorls five, obsoletely striated across, regularly 

 rounded, colour pale, greenish, yellowish, or slightly 

 tinted with reddish, particularly on the body, and mar- 

 gined above by an obsolete white line, on the middle of 

 the body a white vitta revolves, sometimes obscure or 

 wanting; aperture acute, above, regularly rounded at 

 the base, and extending from the centre of revolution or 

 base of the column to an equidistance between the base 

 and the apex of the spire; base of the columella slightly 

 projecting into an obtuse angle; exterior lip whitish, re- 

 flected. 



Length one-fifth of an inch. 



Inhabits P2ast Florida. 



Cabinet of the Acad' my. 



Animal pale; rostrum and tentacula blackish, the lat- 

 ter with a white line; e'^e^ very black, elevated inform 

 of a short tubercle; length about equal to the breadth of 



