V ERMETID/E. M 0 LLU SCA. Steombid^. 
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341 
Family — VERMETID^ {The Worm-shells). 
The animals of this famil}' have a very small rudi- 
mentary foot, not serving for locomotion. It is folded 
on itself, and is truncated or club-shaped in front. 
The body of the animal is irregularly twisted, as is also 
the shell, which is tubular, and attached by its side. 
The operculum is spiral, horny, and circular, when 
present, but it is sometimes wanting. The eggs are 
contained in an oblong membranaceous sac, and the 
young shells are subspiral, rather irregular. 
Genus Siphoniu.m. — This genus, which contains the 
largest species of the familj'’, has the operculum very 
large, smooth, circular,- and concave, with the scar 
central. The shell, which is tubular, is usually fixed, 
and the whirls are always irregularlj'^ twisted when 
adult, and often carinated. The aperture is round. 
In consequence of the shells of this family being alwaj^s 
fixed or attached to other bodies, the animals are 
unable to crawl or glide along ; hence the reason of the 
smallness of the foot. 
Genus Vermetus. — This genus differs chiefly from 
the preceding by the whirls of the large, rather con- 
cave operculum, having a thin, produced, external edge. 
In Vermetxis radicula, a North American species, it is 
horny, black, and hard on the inner, and lamellated on 
the outer surface. It is surrounded by a thin, mem- 
branous, flexible portion, about one-fourth its diameter; 
thus it is enabled to close its shell perfectly at the 
aperture, and yet to retreat far into the narrowed 
whirls. — {Gray.) The shell of the young animal, before 
it escapes from the egg, appears to be helicoid and 
reversed ; but, wdien adult, is irregularly twisted, the 
whirls more or less disunited, and the last generally 
prolonged. 
Genus Siliquaria. — In this genus the operculum 
is manj'-whirled, spiral, and fringed. The shell is 
tubular, internally glos.sy, and irregularly twisted. 
The apex is attenuated, sometimes spiral, and a longi- 
tudinal fissure runs throughout its whole length. The 
species are often found in sponges. 
In the next two families, Strombidce and Phoridcc, 
the animals are distinguished by their having the foot 
compressed, and adapted for leaping instead of crawling. 
The gills are comb-like, and placed on the left side of 
the mantle cavity. 
Family — STROMBID.dS( TheStromh or Wivg-shells). 
The species of this family have a solid spiral shell, 
with compressed whirls and a linear aperture. The 
outer lip changes its form with age, becoming, when 
adult, more or less expanded, and either simple and 
entire at the fore part, or deeply notched. The oper- 
culum is annular, horny, claw-shaped, and serrated on 
the outer side. The Strombs are active, muscular, and 
predaceous animals, using their operculum as a weapon 
of defence. Their eyes are well developed, having 
both pupil and iris, the latter often beautifully coloured. 
The crystalline lens is large, perfectly globular, and 
horn-coloured. “ The perfect development of the large, 
fine, pedunculated eyes of Strombus,” says Mr. A 
Adams in his “Voyage of the Samarang,” “together 
with its veiy elongated, powerful, muscular body and 
foot, and claw-shaped, stout, jagged, horny operculum, 
constitute it one of the most active and intelligent of 
Molluscs. It is, in fact, a most sprightly and energetic 
animal, and often served to amuse me by its extraor- 
dinary leaps and endeavours to escape, planting firmly 
its powerful narrow operculum against any resisting 
surface, insinuating it under the edge of its shell, and 
by a vigorous effort throwing itself forwards, carrying 
its great heavy shell with it, and rolling along in a 
series of jumps in a most singular and grotesque man- 
ner.” The Rev. Lansdowne Guilding affirms that they 
possess the sense of hearing also, or something allied 
to it. 
Genus Strombus. — In this genus the aperture of 
the shell is lengthened, narrow, notched, or having a 
short canal in front, and channeled posteriorly, and the 
expanded outer lip is often lobed and deeply notched 
in front near the canal. In the young state, however, 
the shells present a very different appearance, resembling 
somewhat an ill-formed cone. The species are numer- 
ous, upwards of sixty having been described. They 
are pretty generally distributed, but are by far more 
numerous in tropical seas than in those of temperate 
Fig. 221. 
Strombus Isabella, with animal and eye. 
countries. They are found on reefs at low water, and 
ranging to ten fathoms. The genus is represented by 
the Strombus Isabella (fig. 221). 
THE GIANT STEOMB, or Fountain Shell of the 
West Indies {Strombus gigas), is one of the largest 
living shells, weighing sometimes four or five pounds. 
The animal is occasionally used as an article of diet, 
and the shell is extensivel}' used in the manufacture of 
cameos. Immense quantities are annually imported 
from the Bahama islands for this purpose, and for 
porcelain works. In 1850 three hundred thousand 
shells were imported to Liverpool alone. 
Genus Pterocera. — The Scorpion Shells, as they 
are called, are characterized by the shell having an 
