14 
more than convex ; lateral line somewhat convex ; whorls five, 
obsoletely striated across, regularly rounded ; color pale greenish, 
yellowish, or slightly tinted with reddish, particularly on the body, 
and margined above by an obsolete w'hite line ; on the middle of 
the body a white vitta revolves, sometimes obscure or wanting ; 
aperture acute above, regularly rounded at the base, and extend- 
ing 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 columellar slightly projecting into an obtuse angle ; exterior 
lip whitish, reflected. 
Length one-fifth of an inch. Inhabits East Florida. Cabinet 
of the Academy. Animal pale ; rostrum and tentacula blackish, 
the latter with a white line ; eyes very black, elevated in the form 
of a short tubercle ; length about equal to the breadth of the 
shell ; foot not broader than the body ; tail rounded, or somewhat 
acute ; operculum simple, not spiral, yellowish brown, minutely 
granulated. 
This species we found in great numbers on what are called 
Oyster-Shell Hammocks, near the mouth of the river St. John, 
East Florida, in company with Polygyra septemvolva. When in 
motion the tentacula are elevated and depressed alternately, as if 
feeling the way. 
This shell is certainly a Linnsean Helix, but according to the 
improvements which have been made in Conchology since the time 
of the Swedish naturalist, by Mr. Lamark and other systematists, 
it is at once excluded from that genus and its congeners, by hav- 
ing but two tentacula, and by its operculated aperture. With the 
genus Cyclostoma, as it now stands, our shell has more aflBnity 
than it has to any other, but a very distinct generic character is 
observable in the aperture, which is not orbicular as in Cyclostoma, 
but is almost semi-orbicular, greater in length than in breadth, and 
the lips widely disunited. In addition to the characters usually 
given of the animal of Cyclostoma, Mr. Cuvier remarks that the 
tentacula are terminated by obtuse tubercles ; no such appendages 
are annexed to the corresponding members of this animal. Upon 
these considerations I have thought proper to construct the present 
genus. 
