MOLLUSCA. — 87 
rough shells, with ridges, spines, or tubercles, which are secreted periodi- 
cally, in three or four rows around the shell. The right margin of the 
mantle is divided into lobes, the irregularities of which account for those 
of the shell in the different species. There are about 170 recent and 130 
tertiary fossil species known. 
Harpa (LH. ventricosa, pl. 75, fig. 119) is a genus of finely formed ribbed 
shells of brilliant colors, and a polished exterior. The foot is very large, 
and without an operculum. ‘Ten species are described in Lamarck. The 
genus occurs fossil in the Paris basin. 
Cassidaria (C. echinophora, pl. 75, jig. 121). This genus contains a few 
recent and fossil species. The animal is like that of Cassis, in which the 
foot is longer than the shell, the head proboscidiform, with a projecting 
rostrum and mouth from its extremity. 
Fusus is a genus of marine shells, thickest in the middle, and tapering 
towards both ends; the animal with a small head, ending in two short 
tentacles, the eyes at their external base, but not upon a peduncle or 
thickening of the tentacle, thus differing from Murex and Purpura, but 
allied to Turbinella and Fasciolaria. The head has a terminal slit, whence 
the rostrum issues, and the nucleus of the operculum is terminal. 
Fam. 8. Strombide. In this family the right margin of the aperture is 
dilated, corresponding to the width of the mantle, but this character is not 
present in the immature shells, so that a young Strombus (pl. 75, fig. 114) 
might be mistaken for a Conus (pl. 76, fig. 11). The head is proboscidi- 
form, with a vertical slit from which a long rostrum is extended; the 
tentacles are large, divided at the end, and the truncated extremity of the 
larger external branch bears the large eyes, which have a variously colored 
iris and a cornea, which have not been observed in any of the allied 
families. They live on coral banks at no great depth, and some species 
attain to a considerable size. The locomotion differs from that of most 
gastropoda, being effected by leaping, for which purpose the operculum 
(which has a peculiar shape) is applied to the ground. Strombus lentigi- 
nosus (pl. 75, fig. 114). S. gigas of the Antilles is eight or ten inches 
long, and remarkable for the fine peach blossom tint of the aperture. The 
shell is used to ornament grottoes and gardens, and by sawing off the apex 
it is converted into a rude trumpet. Pterocera (P. chiragra, pl. 75, fig. 
115) differs from Strombus in having the adult shell digitated, and the struc- 
ture of the mantle corresponding with it. /eostellaria (RP. rectirostris, fig. 116). 
Fam. 9. Conide. ‘The shell of the genus Conus (pl. 76, figs. 8-12) is 
obconical, involute, and has a short spire and a narrow aperture as long as 
the body whirl; and the exterior is covered with a periostraca. The genus 
includes many beautiful and highly prized species. Linnzeus described 35 
species, Bruguiéres 146, Lamarck 181, increased to 219 in the last edition 
of 1845, exclusive of 23 European fossil species. At present there are 
probably 300 recent species known. The head is proboscidiform, the eyes 
are upon the middle of the tentacles, the foot is long and very narrow, 
having a corneous sub-spiral operculum, so small in comparison with the 
aperture, that it cannot serve to close the shell. The mantle is scanty (in 
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