205 



uniform fluting, its sub-globose form, its plain, flattened base, 

 and ample tunnel-shaped umbilicus, margined by an overhang- 

 ing carina. 



Cyclostoma flicatum. Testa parva, solida, rudis, pyrami- 

 data, cinereo-virens, plicis confertis obliquis rugata, et striis 

 minutis volvenlibus cincta : spira acuta, anfr. 6 rotundatis et 

 sutura bene discretis, ultimo ad peripheriam rotundato ; infra 

 convexa et umbilico modico acute marginato perforata : apertu- 

 ra circularis ; peritremate simplici. Lat. f , alt. f poll. Hab. 

 Upolu. 



Differs from the preceding in its more elevated, acutely coni- 

 cal form, its plaited whorls without prominent revolving lines, 

 its rounded periphery and base, and its more contracted umbili- 

 cus. The young are discoidal, without folds, but with somewhat 

 nodular spiral lines and bright beryl-green color. 



Cyclostoma obligatum. Testa parva, crassa, sub-globosa, 

 cinerea, arete perforata, utrinque sulcis et costulis acutis sub- 

 crenulatis equalibus cincta, et lineis incrementi subtilissimis 

 striata : spira acuta, anfr. 5 rotundatis : apertura parva, ovata ; 

 peristomate simplici, crasso. Lat. y^^, alt. f poll. Hah. Matea. 



Still smaller than C. rugatum, and remarkable for its solid 

 structure, its coarse alternate ridges and grooves, and its small 

 ovate aperture. It looks not unlike some specimens o{ Littorina 

 rudis. 



Cyclostoma diatretu3I. Testa planorboidea, albido-cornea, 

 supra costis distantibus, ad intervallos cincinne clathratis, angu- 

 lata, late umbilicata : spira planulata, anfr. 4 cylindraceis, rapi- 

 de crescentibus, prope suturam decliventibus : apertura circu- 

 laris ; peristomate simplici. Lat. |, alt. | poll. Hab. Sandal- 

 wood Bay, Feejee Islands. 



Answers very nearly to the description of C. orbcUa, Lk. The 

 whorls increase more rapidly, the costae are more distant above, 

 and the umbilicus is less broad and open. 



Cyclostoma roseum. Testa parva, solida, elevato-conica, 

 glabra, pallide rosea : spira acuta, anfr. 6 convexiusculis, supra 

 arete tabulatis ; sutura bene impressa : apertura spiram baud 

 equans, ovata ; peristomate eversa, acuta ; fissura umbilicali costa 

 circumambiente finita. Lat. |, alt. ^^ poll. Hab. Feejee Islands. 



