HELICID^. 35 



quentl}^ hirsute. H. per sonata, Ijsxm. (yioiy, 31). 4 sp. United 

 States, Europe. 



MESODON, Rfif., 1831. (Patera, Albers, 1850.) Shell umbili- 

 cated or imperforate, depressed globose, striate or costulate ; 

 last whorl deflected near the aperture ; peristome reflected, white ; 

 parietal wall usually obliquely dentate. Shell usually corneous, 

 without bands. M. alholahris, Say (xciv, 38 \ H. muUilinea.ta, 

 8aj, has revolving brown bands, which sometimes coalesce into 

 a uniform brown. 20 sp. United States. 



Ulostoma, Albers, 1850. Shell large, umbilicated, globosely 

 depressed; aperture semicircular; lip reflected, tuberculately 

 toothed at the base ; sometimes with also a small parietal tooth. 

 H. profunda, Say (xciv, 39), 2 sp. United States. 



STROBiLA, Morse, 1864. Shell minute, umbilicated, globosely 

 conic or depressed, obliquely and coarsely striated, smoother 

 below ; whorls 5-6, the last globose ; aperture lunatel}' rounded, 

 peristome thickened and reflected ; the parietal wall and base of 

 last whorl each with two or more revolving lanaellse. Animal 

 with thick, bulbous tentacles, and large eyes. H. labyrinthica, 

 Say (xciv, 18). 4 sp. United States, Mexico, West Indies. 



THELiDOMUS, Swainson, 1840. Shell imperforate or very rarel}^ 

 umbilicated, solid, globosely depressed; spire short, obtuse; 

 whorls four or five, the last contracted and deflected at the 

 aperture, gibbous, obtusel^^ angular on the periphery ; aperture 

 transversely oval ; peristome very thick, reflected, the extremi- 

 ties connected by a wide callus, basal portion of lip often 

 callously tuberculate or denticulate within. 21 sp. West Indies. 

 H. ( Pachy^tovia) GuayHanamensis , Poey (xcvi, 77). 



Z/etoc'/),e?7a, Albers, 1850. (Leiostoma, Swainson, 1840.) Shell 

 imperforate, subglobular, rather solid ; spire short, obtuse, whorls 

 three-and-a-half, the last very large, ventricose ; aperture large, 

 obliquely rounded ; columella arcuated, widely callous; lip cal- 

 lously thickened. H. Jamaicensis, Chemn. (xcvi, 78). Jamaica. 



Pae/iystoma, Albers, 1850. (Otala, Morch, 1852.) Imperforate, 

 very rarel}^ narrowly umbilicate, solid, depressly globose ; spire 

 short, obtuse ; whorls 4-5, the last protracted at the aperture, 

 gibbous ; sometimes obtusely angulated ; peristome thick, the 

 margins callously connected, base callous or denticulate. H. 

 auricoma, Fer. Mostly Cuban. 



Eiirycratera, Beck, 1837. (Parthena, Albers, 1850, part.) 

 Shell umbilicated or imperforate, rather thin, ventricose, obliquel}^ 

 oval ; whorls few, very rapidly increasing, the last greatly de- 

 veloped ; aperture oblong, oblique ; peristome simple or slightly 

 expanded below, the lips united by a thin callus ; columellar lip 

 narrowly reflected. ^. o&H/erflia, Fer. 'xcvi, 81). 20 sp. Hayti. 



Coryda, Albers, 1850. Shell imperforate, globoselj'- conic or 

 depressed ; whorls five and a half, the last anteriorly deflected, 



