GASTEROPODA. 185 
SHELL minute, thin, low pyramidal, almost discoidal, of a dark- 
yellowish ash-colour, minutely lineated with fine radiating, Zlgzag, 
dusky lines. Whorls four or five, the basal one having the periphery 
compressed to a thin, sharp edge, and having a well-marked inter- 
mediate angle between the edge and the suture, which angle is con- 
tinued upon the middle of the smaller whorls. Base slightly convex, 
perforated with a minute, tunnel-shaped umbilicus, and having upon 
it two concentric ridges, with deep grooves undermining them on 
their outer edge. Central area yellowish, with the ridges somewhat 
tessellated with dusky. Aperture very oblique, outline regularly 
arcuated throughout. Operculum horny, multispiral. 
Diameter one-eighth of an inch; axis one-twelfth of an inch. 
Inhabits the Sandwich Islands. 
I have met with no description of a species so small as this, and yet 
its characters are very prominent. Its form and concentric ridges 
give it the aspect of a conical operculum. 
Figures 215, 215 a, two views of the shell, enlarged; 2154, natural 
size. 
Trocuus Licatus (Gould). 
Testa solida, ovato-conica, tmperforata, costulis rotundatis flavescentibus 
ubique cincta, intervallis incarnatis concinné clathratis, ad apicem 
violacea: spira anfractibus sex convexis: apertura circularis ; colu- 
mella recta rotundatd ; labro crenulato: regio umbilicals vix in- 
dentata. 
Trochus lhgatus, GouLp; Proceed. Boston Soc. Nat. Hist., i. 91. 
March 1849. Expedition Shells, 35. 
SHELL ovate-pyramidal, solid, imperforate, everywhere girded with 
rounded, pale-yellowish ribs, about six on the upper whorls, alterna- 
ting with excavated, deep flesh-coloured intervals of about equal width ; 
smooth on the ribs, with delicate lamine of growth in the interspaces ; 
tip violet; spire with six whorls convexly rounded, quite angular at 
47 
