Fi 
Fig. 
Fig. 
Fig. 
Fig. 
iio} 
bo 
= 
EXPLANATION OF PLATES. 
Arca tortuosa L., p. 733. 
Shell of Zrigonia pectinata Lam., p.734. From the inside, to 
shew the hinge (cardo). 
Venus Dione L., Cytherea Dione Lam., p. 742. The shell is 
placed in the position according to which Linnmus has described 
it (see the note, p. 683), namely, with the point, a, downwards ; 
the fisswra, b, forwards ; the lunula, a, backwards. 
Venus (Cytherea) erycina Lam. Right valve from within. 4, ie 
point; a, lunular cavity; 0, fissure; ¢, hinge; d, impression of 
the anterior; e, of the posterior adductor muscle ; f, impression 
of the mantle; g,g, inferior margin of the shell. In this figure 
the shell is placed in its natural position. On the left side the 
fore end is placed, which the animal, when moving, directs for- 
wards. 
s. 8—11. Examples of univalve shells or cochlea, p. 683. 
Shell of Purpura Concholepas, p. 807. 
Shell of Patella, p. 790; Patella umbella Gu. 
. Shell of Scalaria imperialis, p. 798. 
. Shell of Bulimus citrinus Brue., p. 814. Example of a Cochlea 
sinistra, see p. 684. 
PLATE XIV. Mo.ut.uscs. 
Shell of Oliva erythrostoma Lam., p. 810; example of an invo- 
lute shell, p. 683. A, the aperture ; a, external margin ; 3, in- 
ternal margin. 
Shell of Nautilus Pompilius L., divided in the midplane, p. 825, 
an example of a shell rolled upon itself, and at the same time 
many-chambered (cochlea revoluta, polythalamia) pp. 683, 684 ; 
A, A, the last chamber, or cavity, in which the animal lies; a, a, a, 
the siphon which traverses the successive chambers. 
A cover (Operculum) of Turbo, from the inside ; see p. 684. 
Salpa (runcinata ?) p. 699. Of the natural size, from a specimen 
presented to me by Prof. V. BeNEpEN. A, the animal seen from 
the surface which is commonly turned upwards, according to 
Escuricut the ventral surface. Here the muscular belts extend 
throughout; B, the animal seen from the opposite side, where 
the muscular belts are interrupted ; a, (in fig. a) the fissured 
aperture which the animal turns forwards; 6, the posterior 
aperture ; c, the sonamed nucleus, or the collection of the vis- 
cera; d, the salpa chain in process of development ; /, g, muscular 
