Monodonta constricta, Lam.Hist.7 36.
32.

Monodonta rudis (n.s.) Testa ovato-conica imperforata ulbido-purpurea rudis crassa, labro duplicato, extus albido viridi, intus subsulcato, albo.
Inhab.

-- Mus.

Brit.
Shell ovate, conical, imperfurated, rough, pearly, concentrically striated, whitish-brown; when worn or where eroded, purple; the whorls convex, suture distinct, sometimes occupying an impressed line on the lower whorl; the base rather convex, the aperture roundish, the axis (imperforate) covered with a white callus, which leaves a slight concavity over its end; the outer lip of three colours, the outer part purple or green and white, the middle pearly, and the inner opaque, white, and furrowed; the surface of the lower part of the last whorl is frequently worn away just opposite the mouth, so as to leave a purple spot.
33.

Rissoa clathrata (n.s.) Testa subglobosa, subimperforata, alba, solida, spiraliter et concentrice costata; apertura suborbiculari, sutura impressa.
Shell nearly globular, spire conical, upper whorls with three, lower with seven distinct, large, rather separate, much raised, spiral ribs, and numerous acute transverse ribs, which form an acute tubercle where it crosses the spiral ridges, the suture deeply impressed, very distinct, the aperture nearly orbicular, the outer lip denticulated on its outer edge, inner lip smooth, column without any perforation, only a slight linear cavity behind the inner lip, axis and diameter each one-sixth of an inch.
This shell is allied to Littorina muricata (Turbo muricata, Lin.) in its general form and the shape of its umbilicus, but is white and ribbed like Rissoa cimex (Turbo cimex, Lin.) R.calathriscus, the Turbo calathriscus of Montague.
34.