78 HELIX. 



Section VII. CARACOLUS Montfort, 1810. 



Shell depressed, orbicular, carinated, imperforate or narrowly um- 

 bilicate, thick, solid, opaque ; spire conical, apex obtuse ; suture 

 scarcely impressed ; whorls 5 to 6, gradually widening ; the last 

 slightly or not at all deflexed anteriorly ;. aperture transverse, oblique, 

 wider than high ; peristome expanded or narrowly reflexed on the 

 basal margin, its terminations remote ; aperture not toothed within. 

 Type, H. caracolla L. 



Cuba. 



Section VIII. OXYCHONA Morch, 1852. 



Shell conically elevated or depressed, imperforate or umbilicate, 

 acutely carinated or rounded at the periphery, rather thin and light, 

 white with spiral brown zones ; spire conical or depressed, apex sub- 

 acute ; sutures linear ; aperture oblique, generally wider than high ; 

 outer and basal margins of the peristome expanded, thin ; aperture 

 not toothed within. Type, H bifasciata Burrow. 



Mexico to Brazil. 



Section IX. ISOMERIA Albers, 1850. 



Shell depressed, orbicular, rounded or obtusely carinated on the 

 periphery, imperforate or umbilicate, solid, generally dark-brown in 

 color, without spiral bands ; spire depressed, convex, formed of 5 or 

 fewer slightly-convex whorls ; the last whorl deflexed or not anter- 

 iorly ; aperture rounded subquadrangular, transverse, very oblique, 

 wider than high ; peristome expanded or reflexed, somewhat thick- 

 ened, generally bearing small acute teeth, of which one is usually at 

 the position of the periphery ; terminations of peristome remote, 

 joined by a parietal callus ; parietal wall after bearing a small 

 oblique and slightly elongated denticle. Type, H. oreas Koch. 



Northern South America. 



Section X. LABYRINTHUS Beck, 1837. 



Shell umbilicate, depressed, orbicular, carinated, solid or thin, 

 brown ; spire as in Isomeria ; last whorl descending anteriorly, con- 

 stricted behind the peristome ; aperture subhorizontal, transverse, 

 broader than high, obstructed by teeth ; peristome expanded or 

 reflexed all around, continuous across the parietal wall, the basal 

 margin bearing at least two strong teeth, parietal wall with a long, 

 entering lamellar tooth. Type, H. labyrinthus Chem. 



Northern South America. 



