Patella safiana. P. testitudinaria. P. cochlear. P. compressa. P. granularis. P. decaurata. P. Magellanica. P. stellifera. P. vulgata. P. mammillaris. P. lineata. P. leucopleura. P. notata. P. Tarentina. P. punctata. P. puncturata. P. Javanica. P. tuberculifera. P. miniata. P. pellucida. P. tricostata. P. Australis. P. apicina. P. granatina. P. oculus. P. Galathia. P. pectinata. P. viridula. P. scutellar. P. radians. P. cærulea. P. plumbia. P. umbrella. P. pyramidata. P. luteola. P. aspera. P. spinifera. P. longicosta. P. barbata. P. angulosa. P. saccharina. P. laciniosa. P. plicata. · · · · · P. amœna.* P. alternata.* P. alveus.* P. candida.* 5. Genus _Umbrella_. Pl. IX. _Animal._ Body very thick and oval, provided with a dorsal shell; foot large, smooth, and flat, surrounded by a border, anteriorly notched, attenuated behind; head indistinct; four tentacula, the two upper ones thick, short, and truncated, the other two thin, and shaped like pedunculated crests; having foliaceous branchiæ. _Shell._ External, orbicular, subirregular, nearly flat, slightly convex above, white, with apex near the middle; margin acute, internal surface rather concave; having a callous disk, coloured, depressed in the centre, surrounded by a smooth border. Inhabits the Indian Ocean. Two species. Umbrella Indica. U. Mediterranea. 6. Genus _Pleurobranchus_. Pl. IX. _Animal._ Body creeping, fleshy; mantle and foot expanded; branchiæ placed on the right side; cloak enveloping the shell; neck short, contracted in some species, with an emarginate front, exhibiting the commencement of the inferior tentacula, the upper ones tubular and cloven; gills at the edge of the dorsal plait, mouth provided with a short, retractile proboscis. _Shell._ Depressed, oval, oblong, concentrically wrinkled, almost entirely open, rounded and convoluted; the vertex with a single turn. Inhabits the coast of Devonshire in England. Two species. Pleurobranchus Peronii. P. Laqueare. FAMILY III. CALYPTRACEA. Seven genera. 1. Genus _Parmophorus_. Pl. IX. _Animal._ Body creeping, thick, oblong-ovate, broad behind, obtuse at the extremities; border of the mantle cleft before, and suspended vertically around; head distinct, and slit below; two conical contracted tentacula, at the base of which are placed the eyes, which are somewhat pedunculated; mouth below, funnel-shaped, oblique, truncated, and concealed; branchial cavity opening anteriorly behind the head by a transverse fissure. _Shell._ Oblong, very depressed, slightly convex above, obtuse at extremities, anteriorly channeled by a slight sinus, and having towards the posterior part a small pointed apex, inclined backwards; the lower surface slightly concave. Inhabits the Australian seas. Four species. One fossil.