114 
NATURAL HISTORY. [EAST. ZOOL. 
have a very large foot, which is believed to secrete the 
shelly matter of which the lips are formed. The Nassce 
have a moderate sized foot, which is nicked behind, and 
the operculum is toothed on its edge. The Bnllice re¬ 
semble them in most characters, but they have a very 
large broad foot, and the hinder part of the inner lip of 
the shell, being extended beyond the mouth, forms a 
raised enamel band round the suture of the whorls, as is 
also the case with the Ancillarice and some Volutes; 
Phos and Cyllene have a small sinus in the front of the outer 
lip, like the Strombs . The Olives have the shell covered 
with a polished coat, and sunk into the large expanded 
foot, so that only a small part of its back can be seen 
when the animal is walking; the front of the foot is se¬ 
parated from the hinder part, as in the Volutes, by a 
deep nick on each side, and the front of the pillar of the 
shell is obscurely plaited. The true Olives ( Oliva ) have 
a canal round the suture of the whorls, formed to inclose a 
filiform process arising from the hinder end of their small 
inclosed mantle, which is wanting in the Ancillarice . 
Most of these genera are provided with a distinct oper¬ 
culum, except Harpa , the larger species of Olives , and 
the Ancillarice . 
The family of Volutes ( Volutidce, Case ) have a re¬ 
curved syphon, and only a nick in the front of the mouth 
of the shell, like some of the former genera; but the front 
of the pillar of the shell is regularly and obliquely plaited. 
The foot of the animal is very large, partly hiding the shell, 
and generally deeply nicked on each side in front. In 
general the shell is covered with a distinct periostraca, as 
Mitra , Volnta , and Musica, but in a few, as Cymbium , 
the animal, when any sand or other matter gets between 
the shell and the upper surface of its foot, secretes a 
quantity of shelly matter, and covers the adventitious sub¬ 
stance with a glassy coat, so as to prevent the extraneous 
particles from irritating it. In some, as Volnta angulata , 
one of the sides, and in others, as Marginella , both sides 
of the mantle, are produced and reflected over the back of 
the shell, and the shelly matter secreted by these parts 
covers the outer surface of the shell with a polished coat, 
like the Cowries. Only a few species, as Volnta musica , 
and some of the smaller Mitres , are provided with a horny 
