MOLLUSCA. 
92 
2. Cytherea minima, pi. XXXVII, f. 3. 
Cytherea minima^ First Ed., pi. 19? f • 3 ; Cyprina minima, 
Turton, Biv., p. 137; Fleming, p. 444; Venus minima, Mon- 
tagu, p. 121, pi. 3, f. 3 ; Maton and Racket!, p. 81. 
Shell strong, thick, suborbicular, a little compressed ; um- 
bones prominent, acute at the points, and a little turned to 
one side ; outer surface with broad, concentric striae ; of a 
delicate flesh-colour, and very glossy, with two white, diver- 
gent, pretty broad lines, which emanate from the umbones, 
and reach half way down the disks, like the letter V; at the 
extremity of each line is a red streak, diverging outwards to 
the margin ; in some specimens, however, this is wanting ; but 
all of them have spots near the margin ; inside glossy, white ; 
margin plain. Length a quarter of an inch; breadth some- 
what more. 
Inhabits the harbour of Falmouth. 
3., Cytherea minuta, pi. XXXVII, f. 4. 
Cytherea minuta, First Ed., j)l. 19, f. 4. 
Shell nearly orbicular, thick, glossy ; of a deep fawn-colour, 
and wide-set, concentric striae; with two white lines, emanating 
from the umbones, and diverging to the base of the valves, in 
the form of the letter V ; inside glossy, and of a pale pink ; 
margins smooth. Diameter three-eighths of an inch. 
I found a single specimen of this shell on the beach near 
Dunbar, with the animal in it, but in a very decayed con- 
dition. 
This shell differs from the preceding species, in being nearly 
orbicular, and in the triangular lines reaching to the base. 
Genus 12. — Artemis. — Poli. 
Shell nearly orbicular and lenticular, externally and concen- 
trically grooved ; beaks much turned to one side, beneath them 
a short, strongly marked, cordiform lunule; three cardinal teeth 
in each valve, two of which are contiguous, and the other 
divergent and broad in the right valve, cleft in the centre, to 
receive that of the opposite valve, which is slender, with a 
small, lateral, closely approximated tooth ; pallial impression 
with a very large, deeply defined, wedge-shaped, obliquely 
ascending, nearly straight-sided sinus, reaching, in most species, 
two-thirds across the valves ; cartilage subexternal. 
1. Artemis exoleta, pi. XXXVI, f. 1, 3, 19, 20. 
Exoleta orbicularis. First Ed., pi. 20, f. 1, 3, 19, 20 ; Arte- 
mis exoleta, Poli, II, p. L, pi. 21, f. 9, 10, 11 ; Forbes, p. 51 ; 
Venus exoleta, Montagu, p. 116; Donovan, II, pi. 42; Maton 
and Rackett, p. 87, pi. 3, f. 1 ; Turton, Biv., p. 162, pi. 8, f. 7; 
Cytherea exoleta, Lamarck, V, p. 572. 
Shell orbicular, lentiform, strong, moderately convex; with 
numerous, close-set, filiform, regular, concentric striae, and 
many well defined, hollow lines of growth ; anterior side pro- 
vided with a nearly obsolete, longitudinal furrow ; striae on the 
disk, and as far as the umbones, smooth and slightly depressed, 
but thin, elevated, and sharp on the sides ; umbones small, 
approximating, slightly produced, and much turned to one side, 
beneath them is situated a considerably sunk, strongly defined, 
elongated, cordiform, closely and longitudinally striated lunule ; 
external surface of a cream-white, yellowish-brown, or pale 
fawn-colour, frequently with two or three very broad rays of 
[CoNCHACEA. 
rufous-brown, differing in degree of intensity in various speci- 
mens, sometimes the rays consist of an interrupted series of 
triangular spots, and in some instances the surface is nearly 
covered by zigzag lilac markings; inside smooth, white, but not 
glossy, excepting the muscular and pallial impressions ; margins 
plain. Ordinary diameter of the shell an inch and three- 
quarters; but in the Irish Channel it is not unfrequently met 
with measuring two inches and a half. 
This shell is subject to some variation in depth, and when 
full grown the line of junction of the valves is undulated, exhi- 
biting a considerable twist in the seam. 
A variety of this shell was found in the Frith of Forth, by 
my friend James Gerard, Esq., of Edinburgh, with the strise 
wide-set, elevated, and very sharp. 
2. Artemis lincta, pi. XXXVI, f. 2 and 4. 
Exoleta lincta. First Ed., pi. 20, f. 2 and 4 ; Forbes, p. 51 ; 
V mus lincta, Pulteney, Cat. Dorset, p. 34; Venus exoleta, var., 
Maton and Rackett, p. 87, pi. 3, f. 2 ; Cytherea lincta, Lamarck, 
V, p. 573; Cytherea sinuata, Turton, Biv., p. 169, but not the 
figure. 
Shell lentiform, nearly orbicular, slightly elongated, and mo- 
derately thick; with numerous, very fine, filiform, close-set, 
concentric strise, smooth, flattened, and wide on the disk, ex- 
tending to the umbones in the centre of the valves, elevated, 
sharp, and sublamellar on the sides, and numerous, hollow, 
distinctly defined lines of growth, with a longitudinal, slightly 
hollowed furrow on the posterior sides ; umbones a little pro- 
duced, approximate, much turned to one side, beneath which is 
a deeply defined, elongated, cordiform lunule, with exceedingly 
fine, obliquely longitudinal strise; hinge line of the anterior side 
with a long, flattened, lancealate depression, and very fine, lon- 
gitudinally oblique strise ; external surface of a uniform pale 
yellowish-brown, or fawn-colour, sometimes of a livid hue ; 
inside white, but not smooth, except the muscular and pallial 
impressions, together with the entire of the broad space be- 
neath them ; margins plain. Seldom exceeding an inch and a 
half in length. 
This shell is distinguished from the A. exoleta, by its more 
elongated form, and more taper shape towards the umbonal 
region ; by the much finer strise, being nearly double in num- 
ber, and its uniform colour, being always devoid of radiations 
or markings of any kind, and in the hinge line over the liga- 
ment being flattened ; whereas the A. exoleta scarcely exhibits 
any appearance of that character, the twist of the seam is also 
much less in degree. It is liable to considerable variation in 
length, and also in the depth of the valves. 
It is common on most of the British and Irish coasts. 
Turton has properly described the species, but most errone- 
ously given a representation of its congener, A. exoleta. 
Genus 13. — Cyprina. — Lamarck. 
Shell ventricose, equivalve, inequilateral, obliquely heart- 
shaped ; umbones obliquely curved anteriorly ; three cardinal 
teeth in each valve, approximated at their bases, and divergent 
above ; with a posterior, lateral tooth, remote from the primary 
teeth, elevated in the right valve, and receiving between it and 
the margin, the long flat tooth of the opposite valve ; external 
surface covered by a thick, horny epidermis ; each valve with 
