112 HELIX. 



rows of three teeth each, visible through the base. H. POLYGY- 

 RELLA, Bland and Cooper. 



Idaho, U. S., etc. 

 Adelodonta, Ancey, is a synonym. 



Subsection IV. D^EDALOCHILA, Beck, 1837. 



Globosely depressed, costulate above, periphery angulated, base 

 convex, showing more than one sometimes two whorls ; lip ear- 

 shaped, the internal teeth with corresponding exterior constrictions, 

 the extremities of the lip joined by a parietal V-shaped callus. H. 

 AURICULATA, Say. 



So. United States, Mexico, etc. 



Subsection V. SCULPTARIA, Pfr, 1885. 



Discoidal, widely umbilicated, periphery carinate, last whorl a 

 little solute at the aperture; peristome continuous, lip reflected, 

 with three deep lip teeth and one entering parietal lamina. H. 

 SCULPTURATA, Gray. 



W. Africa. 



Section III. STROBILA, Morse, 1864. 



Shell umbilicated, globosely conic, obliquely ribbed, smoother 

 below ; aperture Innately rounded, peristome thickened, reflected, 

 the parietal wall and base of last whorl each with two or more- 

 entering revolving laminae. H. LABYRINTHICA, Say. 



United States, West Indies.. 



Section IV. STENOTREMA, Rafinesque, 1819. 



Shell small, often hirsute, the aperture basal, extending from the- 

 periphery to the axis, parietal wall with a long lamellar tooth, lip 

 broad, usually with a central internal notch, umbilicus usually 

 closed, sometimes open. 



Within the aperture, and near the axis, is an accessory column 

 or pillar, probably assisting the animal in retiring within its shell.. 

 H. HIRSUTA, Say. 



United States.. 



Stenostoma, Raf, 1831, is a synonym. 



Section V. TRIODGPSIS, Rafinesque, 1819. 



Shell of moderate size, depressed globose ; the aperture trilobate- 

 on account of denticles on the superior and inferior parts of the lip 

 and on the parietal wall ; umbilicus closed or open. 



