24 ZONITID^. 



CONULUS, Fitz., 1833. (Trochiscus, Held, 183t. Petasia, Beck, 

 188*7.) Shell small, pellucid, corneous, globosely tftrbinated, or 

 conic, thin, perforate or imperforate; aperture lunar, oblique ; 

 peristome simple. Universal, including several American and 

 European species. Z. fulvus, Drap. (xciii, 98). 



CO NULOPOLiTA, Bottgcr. No umbilicus as in Conulus. H. 

 Baddii, Bottger. Caucasus. 



GASTRODONTA, Albers, 1850. Shell subperforate or umbilicated, 

 orbicularly depressed, light horn-color, sometimes glassy, with 

 more or less numerous wrinkle-like striae ; whorls S-t ; aperture 

 lunate, its base generally furnished with fold-like denticles not 

 reaching its margin; peristome simple, acute. United States. 

 Z. interna, Say (xciii, 100 >. 



VENTRiDENS, Biuuey and Bland, 1869. Shell small, subper- 

 forated or umbilicated, orbicular,- convex ; aperture lunar, with 

 revolving pliciform teeth within the base ; peristome simple, 

 sharp. Z. gularis, Ssiy. Z. suppressa, Say. United States. 



ODONTOSAGDA, Albers, 1860. Shell umbilicated, depressed, 

 thin, white ; whorls six, the last with convex base ; aperture 

 somewhat oblique, lunar, with three double lamellae within ; 

 peristome acute, the columellar margin slightly reflexed. Z. 

 polyodon, Weinland and Martens. Hayti. 



PROSERPiNULA, Albers, 1860. Shell scarcely perforated, dis- 

 coidal, hyaline, transparent ; whorls 4-|, planulate, the last slightly 

 impressed at the base, with a shining callus around the perfora- 

 tion, spiral laminae reaching the margin ; peristome acute. H. 

 discoidea, Ads. 2 sp. Jamaica. 



HELicoDiscus, Morse. Minute, planorboid, with revolving 

 striae, aperture lamellarly toothed within the outer lip. Z. line- 

 atus, Say (xciii, 9, 10). United States. 



MiCROPHYSA, Albers, 1860. (Microconus, Strebel and Pfeffer.) 

 Shell umbilicated, depressed, thin, striulate, scarcely shining; 

 spire flattened with distinct suture ; whorls 4-5, slightly convex, 

 slowly increasing, the last not deflected ; aperture rounded-lunate ; 

 peristome thin, the margin converging. Z. Boothianus, Pfr. 

 (xciv, 15j. 37 sp. West Indies. 



PELLA, Albers, 1860. Shell umbilicate or imperforate, orbic- 

 ular depressed, thin, striate or striately plicate ; whorls five, 

 slightl}^ convex ; aperture Innately rounded ; peristome simple, 

 acute; columellar lip dilated, reflected, free. H. hisculpta, Ben- 

 son (xciv, 16). So. Africa. 



SAGDiNELLA, Morch, 1872. Not characterized. H. Didrich- 

 senii, Morch. Nicobar Is. 



STRiATURA, Morse, 1864. Central plate of the radula enormous ; 

 buccal lamina almost smooth, with a median furrow and notch. 

 Z. milium, Morse. United States. 



JANULUS, Lowe, 1852. Shell umbilicated, depressed orbicular. 



