HELICID. 29 
Hyalosagda, Albers,1860. Shell scarcely perforated, depressed 
hyaline, thin ; whorls 5—7, the last excavated at the base; aper- 
ture obliquely lunar; peristome acute, columellar margin scarcely 
dilated, slightly reflexed. H. stmilis, Adams. Jamaica. 
PATULA, Held, 1837. (Eyryomphala, Beck, 1837. Delompha- 
lus, Agassiz, 1837. Euryomphala, Herm., 1846. Discus [part], 
Ads., 1855.) Shell perspectively umbilicated, discoidal or tur- 
binated, depressed, rugose or striated; whorls gradually enlarg- 
ing; aperture rounded, unarmed by teeth; lip simple, sharp. 
Jaw smooth or slightly striated, with a more or less marked 
median projection. 327 sp. Universal. 
Pyramidula, Fitz., 1833. H. rupestris, Drap. Europe. 
Patulastra, Pfeiffer, 1878. Uncharacterized. H. ampla, Pfr. 
Mexico. 
Discus, Fitz., 1833. H. perspectiva, Say. United States. H. 
rotundata, Mull. (xciii, 6). Hurope. 
Planogyra, Morse, 1864. Shell minute, perfectly flat above, 
umbilicus moderate; whorls very convex, the last one sharply 
ribbed. H. asteriscus, Morse (xciii, 7). United States. 
Gonyodiscus, Fitz., 1833. H. solaria, Menke. Europe. 
Acanthinula, Beck, 1846. (Zoogenites, Morse, 1864.) Shell 
perforated, globosely turbinated, with a brownish plicately 
ribbed or aculeate epidermis; whorls 4-5; aperture rounded ; 
peristome thin, somewhat expanded, its extremities approaching. 
H. harpa, Say (xciii, 99). H. aculeata, Mull. (xciv, 40). 8 sp. 
United States, West Indies, Europe. Buccal plate transversely 
and longitudinally striate, its edge slightly indented with a 
middle projection. Viviparous, containing embryos in various 
stages of development at the same time. 
Trichodiscus, Strebel and Pfeffer. Shell subdepressed, widely 
umbilicated, banded, beset with fine bristle-bearing warts ; peris- 
tome shortly reflected. H. coactiliata, Fer. Mexico. 
Thysanophora, Strebel and Pfeffer. Shell flat or conical, 
widely umbilicated, brown, with longitudinal plaits and rows of 
epidermal fringes; aperture simple. H. impura, Pfr. Mexico. 
Lyra, Shuttlew. Shell with revolving lines. Canaries. 
Patulopsis, Strebel and Pfeffer. Shell nearly flat, keeled, 
ribbed, with wide umbilicus. H. carinata, S.and P. Mexico. 
Pseudohyalina, Morse, 1864. (Chanomphalus, Strebel and 
Pfeffer.) Distinguished from Patula by the minute size and 
more moderate umbilicus. P. minuscula, Say, etc. United 
States, Mexico, ete. 
Anguispira, Morse, 1864. Shell large, depressed turbinate, 
banded or striped; umbilicus moderate. P. allernata, Say 
(xciii, 8). United States. 
Stephanoda, Albers, 1860. Shell widely umbilicated, thin, 
depressed, plane above, convex below, with 5-7 close volutions, 
