98 HELIX-LUCERXA. 



Lip scarcely expanded above. 



Teeth of basal lip two ; extending more than half-way to parietal 

 wall, lucerna. 



Teeth of basal lip not extending half-way to parietal wall, 



Edge of whorls undulating, chemnitziana. 



Edge of whorls smooth, 



Basal lip adnate for a considerable distance to the base, 



subacuta. 

 Basal lip adnate only near and over umbilicus, acuta. 



B. SPECIES WITH THREE OR FOUR TEETH ON THE BASAL LIP OF 

 PERISTOME. 



Body-whorl flattened, depressed, acutely carinated, 

 Shell unicolored, brown, 



Cariiia very acute ; size large, >eraeufo's-sz'wa. 



Carina less acute ; diam. under 36 mill. cam. 



Shell conspicuously banded, 



Center of base dark, soror. 



Base with a dark girdle, center light, 



Acutely carinated, lip 4-toothed, scliroeckeriana. 



Obtusely carinated, lip 3-toothed, tridentina. 



Body-whorl globose-depressed ; obtusely carinated or rounded; with 

 a short furrow or groove above the peripheral carina, and parallel 

 with it, a short distance behind the peristoitie. 



Body- whorl decidedly depressed ; umbilicus open ; 4 teeth equally 

 spaced. 



Parietal wall elevated ; peristome solute, anomala. 



Parietal wall adnate, sinuosa. 



Body-whorl globose-depressed ; imperforate or umbilicus narrow, 

 Outer tooth abruptly bent outward at its inner end, sinuata. 

 Outer tooth parallel with the adjacent tooth, 



Diam. 24 mill, or more, simson. 



Diam. 23 mill, or less, invalida. 



Body-whorl globose-depressed, obtusely carinated or rounded, with- 

 out any furrow or groove above the periphery behind the aperture. 

 Outer two teeth of base contiguous, decidedly united at the base, 

 3 furrows behind peristome, 



Fourth (outer) tooth the smallest, okeniana. 



Outer tooth not smallest, sloaneana, bronni, valida. 



Outer two teeth scarcely or not at all united at base, 



