ZONlTIDiE. 23 



STENOPUs, Guildiiig, 1828. (Guppyfi, Morcli, 1867. Habro- 

 conus, CrosSe and Fischer, 1872.) Animal with a narrow loco- 

 motive disk, and a border on either side, as in Yaginula ; caudal 

 gland with a retractile appendage. Shell perforated, conical or 

 depressed, thin, diaphanous; peristome simple. 5 sp. St. 

 Vincent, W. I., Mexico, Venezuela. S. cruentatus^ Guild (xciii, 

 91). St. Vincent, W. I. 



OMPHALINA, Rafinesque, 1819. (Moreletia, Gray, 1855. Edusa, 

 Albers, 1860. Zonyalina, von Martens, 1865.) Shell widely 

 umbilicated, striated above, smooth below. Labial palpi large, 

 caudal pore well developed. 14 sp. United States, Mexico, 

 Guatemala. Z. fuUginosus, Griffith (xciii, 96). IT. S. Zonya- 

 lina is said to be distinguished from Moreletia by the want of 

 the outer cervical lobe of the mantle. 



MEsoMPHix, Rafinesque, 18L9. Shell umbilicated or perforated, 

 globosely depressed, thin, striated, reddish horn-color, lighter 

 below, shining ; whorls four-and-a-half to six ; aperture lunar 

 ovate; peristome simple, straight, acute, extremities approach- 

 ing, that of the columella subreflexed. Z. ligefus, Say (xciii, 

 97). Several species, mostly Ifnited States. Barely distin- 

 guished from Omphalina by a more elevated spire. 



^GOPiNA, Kobelt. (Retinella, Shuttl.) Proposed for Z. olive- 

 torum, Gm. (xciii, 95), and allied European species, scarcely 

 distinct from the North American group Omphalina. 



HYALiNiA, Agassiz, 1837. (Aplostoma, Moquin-Tandon, 1855.) 

 Shell depressed or conical, more or less longitudinally, but not 

 spirally striate; semitransparent, smooth and shining; umbilicus 

 large, rarely small or none ; epiphragm none, rudimentary or 

 vitreous. Flagellum none or short, thick and steadied by a 

 terminal muscle; mucous vesicles represented by a glandular 

 layer. 50 sp. Mostl}^ Europe and North America, Z.cellarius^ 

 Miiller. 



viTREA, Fitz., 1853. (Crystallus, Lowe, 1854.) Shell small, 

 fragile, shining, h^^aline, smooth, convexl}^ depressed, perforate 

 or imperforate ; whorls 4-6, the last not deflected at the 

 ajDerture ; aperture lunate, the lip simple, acute. Europe. H. 

 crystallina, Miill. 



POLiTA, Held, 1837. (Oxychilus, Fitz., 1833. Lucilla, Lowe, 

 1854. Aplostoma, Moquin-Tandon, 1855. Euhyalina, Albers, 

 1857. Hyalina (restricted), Albers, 1860.) Shell convexly 

 depressed or subdiscoidal, umbilicate, smooth, shining, pellucid, 

 corneous, the base more or less milky opaque; aperture obliquely 

 lunate ; lip simple, acute. Mostly European. H. glabra, Stud, 



ZONITOIDES, Lehm,, 1864. H. nitida, Miill. Europe, United 

 States. 



NAUTiLiNUS, Mousson, 1872. Shell nautiloid, involute. H. 

 Clymene, Shuttl. 



