EXPLANATION OF THE PARTS OF SHELLS. 15 
Body of the shell is the first or lower whorl of the spire, in 
which the aperture is situated, and is in general longer than the 
remaining whorls. Plate II. figs. 10 and 12, #' F'; and Plate III. 
figs. 7 and 9, F F. 
Front of the shell is that side where the aperture is situated. 
Plate II. fig. '7, 7; and Plate III. fig. 8, 7. 
Back is the opposite side to that in which the aperture is 
placed or turned directly from the observer. Plate III. figs. 5 and 
10, G G. 
The venter, or belly, is the most prominent part of the lower 
whorl or body, generally situated in the vicinity of the lip over the 
aperture; and formed by the convexity of the aperture. It is in 
general only made use of in describing shells whose body is large 
in proportion to the size of the spire. Plate III. figs. 5 and 10, 
HH. 
Sides. 'The extreme edges of the shell, when viewed either in 
front or from the back. Plate Il. fig. 11,K KKK KKK RK. 
Right side is, when the shell is viewed in front that side next 
the observer’s left hand. Left side, the side with the aperture 
in it. 
Aperture, or mouth, is that part of the lower whorl or body 
by which the animal protrudes itself. This is one of the principal 
generic distinctions of Univalve shells, and differs very much in 
shape ; some apertures being rounded, others semilunar, angular, 
&c. Plate II. figs. 9 and 11, € C; and Plate III. figs. 1, 3, and 
14, C C C. Some apertures have a canal at their base, and 
others are devoid of it. In various genera it extends the whole 
length of the shell, as in the Cyprea, and some of the Cones with 
depressed spires. This in several individuals is either entirely 
open, or is closed by an operculum or lid, which is usually affixed 
to the foot of the animal. 
Canal, or gutter, is the inside of the elongations of the aper- 
ture, or both lips of the shell of those species with a beak, in 
which it forms a concave channel or gutter, running from its 
commencement in the aperture to the extremity or base. Plate 
II. figs. 10 and 11, Q Q. Plate III. fig. 8, Q@. Some species are 
furnished with two canals, one situated at the junction of the outer 
lip and body, as in the Murex. 
