176 UMBRACULUM. 
Subgenus Umbraculum. Shell sinistral, with growth-lines and 
some faint, low, wide-spaced radial ridges (page 117). 
Subgenus Hyalopatina Dail. Shell dextral, the nucleus sinistral ; 
sculptured with very numerous radiating lines of minute elevated 
points (page 184). 
See also, Bertinia Jousseaume (page 189). 
Genus TyLtopina Rafinesque, 1819. 
Foot long-oval, without anterior sinus. Head large, with prom- 
inent anterior tentacles. Gill a short bipinnate plume on the right 
side posteriorly. Penis retractile, on the right side in front of the 
gill. Shell with the edges not calcified, vertex subcentral (page 185). 
Genus UMBRACULUM Schumacher, 1817. 
Patella sp. of GMELIN, MArryn and some other early authors. 
Acardo Lam., (in part), Syst. An. s. Vert., p. 180 (1801).— 
MEGERLE von MUHLFELD, Gesellsch. Naturforsch. Fr. Berl., Mag. 
fiir die Neuesten Entdeckungen, etc., v, p. 63 (1811).—Not Acardo 
Commercon MS. in Bruguiére, Encycl. Méth., i, p. 1 (1792),—Epi- 
physis of whale, teste Deshayes, Encycl. Méth., edit. 1830, p. 1. 
Umbraculum ScHUMACHER, Essai Nouv. Syst. Vers Test., pp. 
bondi (sit): 
Gastroplax BLAtNy., Bull. Sci. Soc. Philomathique for 1819, p. 
182. 
Umbrella LAMARCK, Anim. s. Vert., vi, p. 343 (1819). 
Ombrella BLAINVILLE, Dict. Sci. Nat., xxxii, p. 267 (1824). 
Umbella Ors., Moll. Cuba, i, 115 (1841). 
Operculatum H. & A. Av., Gen. Rec. Moll., ii, p. 41 (1854), and 
of Linné, Mus. Tess., 1753, not binomial. 
Shell patelliform, depressed, sinistral ; the vertex to the left of and 
somewhat behind the center, usually colored, more or less conically 
elevated, apex curved backward, when perfect forming a minute 
spiral of scarcely over one whorl. 
Soft parts much larger than the shell. Foot very voluminous, 
tuberculate above, with the sole very broad, oval; deeply slit in 
front, the mouth situated at the bottom of the sinus, with plate-like 
labial processes in front of it. Head projecting but little in front of 
mantle, bearing two tentacles slit down their outer sides, the small 
eyes at their inner, anterior bases; penis in front of head, lying in 
