16 INTRODUCTORY 



Beak is that lengthened process in which the canal is situate ; 

 it commences a little higher up, on the outside, than the insertion 

 of the canal in the inside, which is always distinctly marked by the 

 line of the aperture. Plate II. fig. 11, p. This process is not so 

 conspicuous in some of the species of Voluta,but is more marked 

 in the genera Murex, Fusus, Pyrula, &c. 



Pillar, or columella, is that process which runs through the 

 centre of the shell in the inside from the base to the apex in 

 most univalve shells, and appears to be the support of the spire : 

 and, indeed, seems to form that part of the shell: it is in general 

 grooved or folded ; but, as it is situated in the interior of the shell, 

 a minute description is unnecessary. Plate II. figs. 10 and 12, 

 M M MMM', and Plate III. fig. 9, M M M. The internal 

 edge of its base is frequently described as having plaits, &c. 



Plaited Columella are those folds, or plaits, which are the dis- 

 tinguishing characteristic of the Volutae and other genera. Plate 

 II. fig. 7, z. 



Pillar Lip is a continuation of the glossy process with which 

 the aperture is lined, and expanded on the columella. Plate III. 

 figures 7 and 8, O O. This is termed the inner lip by some 

 authors. 



Outer Lip. The expansion, or continuation of the body of 



the shell on the left margin of the aperture, and is also lined 



with the glossy process of the aperture. Plate II. fig. 7, J\''\ and 



Plate III. fig. 8, JV* JV J\\ The latter is an example of the alated 



^or winged shells. 



Operculum, or lid. This is only an appendage to the turbi- 

 nated or spiral shells affixed to the foot of the animal, sometimes 

 of a testaceous, in others of a horny or cartilaginous substance. 

 It acts as a door or lid, and is calculated for the protection of the 

 animal, when it retires within its dwelling, from the intrusion of 

 its enemies, and adapted to the shape of the aperture, which it 

 closes nicely up : as exemplified in the operculum of the Turbo, 

 and is of a hard, stony appearance. Plate III. fig. 4. 



Spire consists of all the whorls of the shell, except the lower 

 one, which, as before observed, is termed the body of the shell. 

 Plate 11. fig. 12, 2>; and Plate III. figures 7 and 8, D B. 



The spire is a prominent feature of the Univalve ; and upon 



