164 PECTINIBRANCHIATA.—CYPREADA. 
posterior part of the foot of the animal, and fitting 
the interior of the mouth of the shell when the 
animal retreats within the cavity. 
The most important difference between the 
animals of this order consists in the presence or 
absence of a canal, formed by a lengthening of the 
lung-chamber of the left side, which is carried 
along a similar canal in the shell, or through a 
simple notch, to enable the animal to respire with- 
out the need of quitting its shelter. The presence 
or absence of an operculum is also a distinction ; 
and the filaments, fringes, and other ornaments, 
which are occasionally carried on the head, the 
foot, and the mantle, afford other characters for the 
subdivision of this extensive Order. 
FAMILY CYPREHADA. 
(Cowrves.) 
Of this extensive group of shells, the majority 
of which are so exquisitely beautiful that they form 
the ornaments of cabinets, and the pride of collec- 
tors, a single British species is a sufficient warrant 
for noticing, in this volume, so attractive a family. 
Most of them are inhabitants of the tropical seas, 
residing chiefly near the shore, on reefs, and among 
rolled masses of broken coral; hence archipelagos 
and smaller groups of islands are peculiarly rich in 
the lovely Cowry-shells. There the brilhancy and 
variety of colour displayed both by the shells 
themselves and by the animals, accord with the 
glories of those latitudes, where the hght and heat 
of a vertical sun give the greatest stimulus to 
animal and vegetable life. 
