TABULAR SCHEME. 71 



Height less than breadth 



Mouth almost circular Cyclostrem-a, 335-337. 



Thin and green Vitrina, 247. 



Thin and opaque, mouth flexuous and projecting 



Skenea, 434. 

 Thin, transparent and shining, mouth obliquely cres- 



centic Zonites, 248-258. 

 Mouth semilunar Helix, 263-287. 



Base flat 



Outer lip waved Adeorbis, 438. 

 Outer lip plain Trochus, 338-354. 



Height equal to breadth 



Shell purple lanthina, 357-359. 



Shell conical with flat base Trochus, 338-354. 

 Pillar folded Limncea, 207-214. 

 Pillar grooved Lacuna, 392-396. 

 Shell thick and heavy Littorina. 387-391. 

 Shell thin and light Helix, 263-287. 

 Mouth circular Valvata, 441, 442. 



Height more than double the breadth 



Between double and treble the breadth 

 Pillar folded Limncea, 207-214. 

 Outer lip reflected (land shell) Bulimus, 259-262. 

 Inner lip reflected (land shell) Acicula, 398. 

 Upper whorls sinistral Odostomia, 468-502. 



Height over treble the breadth 



Upper whorls sinistral Odostomia, 468-502. 

 Subulate and polished Eulima, 461-466. 



Pyramidal 



Smooth or faintly ridged Aclis, 365-369. 

 With bold spiral ridges TurriteUa, 452. 

 With bold longitudinal ribs Scalaria, 360-364. 



Height less than double the breadth 

 Peristome incomplete 



Shell thin, smooth, and glossy Jeffreysia, 435-437. 

 Shell semi-globular, mouth semi-circular Neritina, 



356. 



Mouth horseshoe-shaped Bulimus (obscurus), 262. 

 Pillar with fold Limncea, 207-214. 



Peristome complete 



Pillar with groove Lacuna, 392-396. 



Sinistral Physa, 227-229. 



Amber-coloured, mouth more than half the height of 



the shell Succinea, 313-317. 



Richly variegated and polished Phasianclla, 355. 

 Inner lip thick, outer lip sharp Assiminec, 432, 433. 



