MANUAL OF THE MOLLUSCA. 
ANAULUS, Pfeiffer, 1855. 
Type, A. bombycinus. Borneo. 
Shell umbilicated, pupineeform , peristome double, internal 
continuous, external dilated, perforated at the margin by a 
canal; canal sutural and internal, terminating anteriorly, and 
embraced by the outer portion of the double peristome (it can 
be traced externally along the last whorl), and reaching into 
the concavity of the spire. Operculum very thin, corneous; 
narrow-whorled. 
Distribution, 3 species. East Indian Archipelago. 
“‘The use of the sutural tube seems to be the preservation of 
@ communication with the external air when the aperture is 
closed.” —( Benson. ) 
OPISTHOSTOMA, Blanford, 1860. 
Synonym, Plectostoma, Adams, 1865. 
Type, O. Nilgirica, Blanford. The Nilgiris, India. 
Shell pupiform, umbilicated, with a regular costulated orna- 
mentation; apical whorls obliquely distorted; last whorl 
strangulated, separated from the others, and applied to the 
penultimate; peristome double, free portion prolonged back- 
wards; operculum horny (?) 
_ O. De Crespigni, Adams (Plectostoma), has a conical spire, and- 
the apical whorls are not excentric to the axis of the lower 
whorls, as they are in the ovate spire of O. Nilgirica. 
Distribution, 5 species. India, Borneo, West Africa. 
[Faminy PROSERPINIDZ. | 
Animal with a short annulated muzzle; tentacles two lateral, 
subulate ; eyes subsessile on the outer side of the base of the 
tentacles; sides simple; foot moderate, truncated in front, 
acute, and keeled above behind, with a concavity in the front 
part; lateral and central teeth large, irregular, lobed, or den- 
tated; operculum wanting. 
Shell heliciform, shining, imperforated; base callous; the 
septa between the upper whorls absorbed as in Helicina and 
Stoastoma. . 
This family is most nearly related to Helicinide. 
CERES, Gray, 1856. 
Etymology, Ceres, the goddess of corn. 
Type Carocolla eolina, Duclos. © 
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