MANUAL OF THE MOLLUSCA. 



Anaitltjs, Pfeiffer, 1855. 



Type, A. bombycinus. Borneo. 



Sliell umbilicated, pupinseform ; peristome double, internal 

 continuous, external dilated, perforated at tbe 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 wborl), and reaching into 

 the concavity of the spire. Operculum very thin, corneous; 

 narrow-wborled. 



Distribution, 3 species. East Indian Archipelago. 



' ' The use of the sutural tube seems to be the preservation of 

 a communication with the external air when the aperture is 

 closed." — (Benson.) 



Opisthostoma, Blanford, 1860. 



Synonym, Plectostoma, Adams, 1865. 



Type, 0. 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 (?) 



0. 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 sj)ire of 0. Nilgirica, 



Distribution, 5 species. India, Borneo, West Africa. 



[Family PBOSERPniriD^.] 



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 Helicinidce. 



Ceees, Gray, 1856. 



Etymology, Ceres, the goddess of corn. 

 Type CarocoUa eolina, Duclos. 

 .48' 



