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very numerous, this family contains feme very 
beautiful and curious Shells. 
The cafTides or helmets, conftitute the twelfth 
family. Thefe are defined to be femi-globofe 
Shells, with the back very convex and round, and 
the under or mouth part flat. They have alfo 
fiat, or at lead very fliort clavicles or turbans; 
the mouth is long, narrov.'ifh, and terminates at 
the top in a gutter, v/hich turns vcrv large, ftrong, 
and wrj on the back. The lip is always ftrongly 
and thickly toothed, and rifes into a high thick 
border or ledge on the upper part or back; and 
the pillar is generally flrongly toothed and ridged, 
or fct with fnall afperities. Lifter and Linnfeus 
rank thefe Shells among the buccina. They are 
not very numerous; but fome of them are ex- 
tremely large and weighty. 
The thirteenth family is the trochi, or tops, 
which are Shells of a conic or pyramidal fliape, 
the top being broad and flattifli, and gradually 
tapering thence to a very fharp point. The aper- 
ture or m.outh is generally angular, low, and nar- 
row. It is a very numerous family, and abounds 
in curious and elegant Shells. 
The fourteenth family is the cochlete, or fnails ; 
the charafler of which is, around, or nearly round 
mouth, perfeftly bordered, and circumfcribed. 
Da Cofta divides this flimily into five genera ; the 
nerites, or fnails, with femicircular mouths; he- 
lices, oi' round- moutlied fnaih, whofe fpires lie 
horizontally, or between tv/o levels, of v/bich ge- 
nus there are niany curious fpecies; fnails with a 
fhortor fiat turban, to which belong the common 
land-fnails, and many others ; iriails v/ith a length- 
ened clavicle or turban, v/hich may be denomi- 
nated turbo ; and the cochlese ftrombiformes, or 
fnails whofe turbans are extremely long and flen- 
der, of which genus the fpecies are few. 
The buccina, or whelks, conftitute the fifteenth 
family. Thefe are Shells whofe mouth is an ob- 
long and verv lengthened oval, the upper part 
whereof is pro luced into a gutter or flight beak. 
Accordingly D.i Cofta divides this family into fix 
genera. The buccina canaliculata, or guttered 
vv-heiks, the upper part of whofe mouth ends in 
an abnoft ftraight and fomewhat prolonged gut- 
ter; and the inner, or columella lip, is always ex- 
tremely fnooth. The fpecies of this genus are 
very numerous. The buccina recurviroftra, or 
wrv-m.outhed whelks, whofe mouth appears as if 
cut fnort at the top ; for the gutter or beak does 
not extend ftraight forward from the upper part 
of the triouth, but bends or falls on the back in a 
wry manner, exaftly like the mouth of a flat fifh. 
There are many fpecies belonging to this genus. 
The buccina roftrata, or longiroftra, or beaked 
Iks : thefe have a very lengthened beak, fuch 
as the purpuras, tower of Babel, crane, and many 
other rare and curious ipecies. The buccina 
umbilicata, or umbilicated whelks, v^'hich have a 
perpendicular hollow or navel by the fide of the 
columella or pillar lip, on the firft or body whirl. 
There are but few fpecies of this genus. The 
buccina columella dentata, or plicata, or vv'hclks 
with a wrinkled or plaited pillar. And, laftly, 
the ftrombi, or needles, which are Shells with a 
very long and taper clavicle or turban, and a wry 
mouth turning on the back, in lome fpecies of 
fuch a length that it refembles a fpur. The ge- 
nus of ftrombi is pretty numerous. 
The fixteenth family is the murices, whofe di- 
flinguifiiing characlcriftic is an oblong and equally 
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narrow mouth longitudinally, which runs into d 
fhort gutter or top ; and they are always thorny, 
fpiked, or rough, over the entire furface, like the 
fpikes or afperities of rugged rocks, whence the 
Latin appellation murex, the Englifli rocks, and 
the French rochers. 
Da Cofta divides this family into four genera. 
The murex, rocks, or thofe Shells that have a 
long and equally narrow mouth; and are gene- 
rally very rugged, with a clavicle or turban ufu- 
aliy fliort, and almoft flat, and the pillar wrinkled 
or plaited; of which there are many fpecies. The 
rhombi, or Shells whofe fiibord inate charafter is, 
that they have always a rhombic fhape or contour; 
of which the fpecies are not very numerous, but 
fome are large and heavy. The alatse, or winged 
Shells, whofe lip is expanded outwards like a flap 
or wing; and which are ranked by Linnseus under 
the genus of ftrombus: of this genus there are 
many fine and beautiful fpecies. And the apor- 
rhoidfc, or winged Shells, whofe edges are befet 
with ftrong fpikes or procefl^es, like fingers, as the 
fpiders, devil's claws, and others. The fpecies 
are few; but the general beauty of them amply 
compcnfates for the numbers. 
The fecond grand divifion or clafs of Shells 
comprehends the bivalves, or fuch Shells as are 
compofed of two pieces or parts; which being 
connected by hinges, play on each other, fo as to 
fhut, open, and perform all the fundions neceiTarv 
to the ceconomy of the inclofed animals. 
Da Cofta diftributes bivalves, of which there 
are no land, and few frefl:i-water Shells, into three 
orders. The firft includes thofe Shells that have 
unequal valves, and fluit clofe; of which there are 
four families. 
The firft family is the pedens, or efcallops| 
the cflTential charafter of which is a trigonal finus, 
and an elaftic cartilage for it's hinge in the cen- 
tre of the top of the Shell: the fubordinate diftinc- 
tions are their being eared; and that the top runs 
into a perfeclly llraight line, gradually widening 
thence into a round bottom. Linnfeus makes 
the peden a genus of oyfters. Gualtieri divides 
them into different genera, with equal and un- 
equal valves; calling the former peflen, and the 
latter concha pedlinata; and theefcaliops with un- 
equal or fingle ears, he denominates peftunculi. 
The fpecies are numerous; fome of which arc 
very beautiful and curious, as the ducal mantle, 
the compafs or fole, the duck's foot or coral, and 
the efcallop. 
The fpondyli conftitute the fecond family. 
Thefe Shells are generally eared with unequal 
valves, partaking of the ruggednefs of the oyfter, 
v.'ith fomewhat of the efcallop form, fb as to feem 
a medium between the two families. However, 
the fpondyles, like the efcallops, have fome fpe- 
cies with equal valves, and without ears. The 
chief charafter is the hinge, which in the upper 
Shell confifts of a triangular hollow and cartilage, 
like the efcailop, in the very centre; on each fide 
of which there is a large thick and prominent 
tooth or joint lying on each fide of the cavity. 
This family is not very numerous in it's fpecies. 
The third family is the oftreum or oyifer; the 
hinge of which is deftitute of teeth; but there are 
procefi"es of a large inarticulate gutter running 
along the length of the top of the Shell, in both 
valves alike, covered and filled v/ith a ftrong car- 
tilage. 
The fpecies of this family are very numerous: 
fome 
