70 MOLLUSCA. 
Maton and Rackett, p. 102; Lamarck, VI, pt. Ist, p. 228; 
Fleming, p. 395; Brown, Ency. Brit., p. 4223 Ib., Wernerian 
Mem., p. 514; Turton, Biv., p. 229, pl. 18, f. 5, 6, 73 Forbes, 
p- 38. 
Shell suborbicular, smooth, thin, membranaceous, and trans- 
parent, generally much compressed ; convex yalve a little 
thickened; flat valve very thin, with a large perforation, for the 
size of the shell; outside dull yellowish-white, with very indis- 
tinct, concentric wrinkles, or lines of growth, which can only 
be seen by the aid of a strong lens; inside white, with pale 
iridescent reflections; plug tendinous, very seldom hard at the 
base, with the termination testaceous ; umbones small, flat, and 
pointed. 
Common on all the British and Irish coasts, adhering to 
shells, stones, and F'wci. 
4, ANomia acuLEata, pl. XXII, f. 6. 
Anomia aculeata, First Ed., pl. 34, f.6; Gmelin, Syst., p. 
3346; Miiller, Zool. Dan. Prod., p. 3005; Montagu, p. 157, 
pl. 4, f.5; Fleming, Edin. Eney., p. 98; Ib., Brit. An., p. 396; 
Brown, Ency. Brit., p. 422; Ib., Wernerian Mem., p. 514; 
Maton and Rackett, p. 103; Turton, Biy., p. 233. 
Shell thin, compressed, orbicular, or slightly oblong ; 
numerous raised, divergent, interrupted strie, which are sur- 
with 
mounted with many small concave, obtuse murications, or 
spines; umbones small, turning a little downwards; upper valve 
convex; under valve quite flat and smooth, but sometimes pro- 
vided with small murications towards the margin; perforation 
of medium size, and situate near the hinge; generally of a pale 
dull brown, or cream-white; inside white, and slightly pearlace- 
ous. Diameter three-eighths of an inch. 
Found on many of our coasts, adhering to the roots of Alga, 
stones, the legs of crabs, &c. 
5. ANOMIA CYLINDRICA, pl. XXII, f. 7, 8. 
Anomia Cymbiformis, First Ed., pl. 34, £7, 8; Maton and 
Rackett, Linn. Tr., VIII, p. 104, pl. 3, f. 6; Fleming, Edin. 
Ency., p. 98; Anomia cylindrica, Schréeter, p. 3, pl. 9, f.95 
Brown, Ency. Brit., p. 422; Fleming, p. 395; Turton, Biy., p. 
232; Forbes, p. 39. 
Shell oblong-oyal, convex, somewhat cylindrical; beaks re- 
curved, narrower towards the umbones; upper valve convex, 
and curving over the under one, which is concave and smooth ; 
surface of upper valve dull brown, with a few transverse, obscure 
wrinkles. Length half an inch; breadth a quarter. 
Inhabits many of our coasts, adhering to Fuci, Sertularia, &c. 
6. Anomia ELEcTRICA, pl. XLVI, f. 5. 
Patella pellucida, First Ed., pl. 10,* f. 5; Brown, Wernerian 
Mem., II, p. 514; Anomia electrica, Linné, Syst., p. 1151; 
Chemnitz, VIII, p. 79, pl. 76, f. 691; Turton, Biv., p. 226, pl. 
17, f. 8, 9. 
Shell orbicular, very thin, pellucid, slightly wrinkled concen- 
trically; umbo small and margined, below which is a chalky-like 
spot, of a roundish shape; upper valve very convex; under valve 
very flat, with an extremely large interrupted perforation; whole 
shell of a bright amber-colour. Diameter about an inch. 
I first found this species at Color Cots, near Tynemouth, and 
afterwards at Dublin Bay and Portmarnock, Ireland. 
7. ANomIA cEPa, pl. XXXIX, f. 12. 
Anomia cepa, Linné, Syst. p. 1151; Chemnitz, VIII, p. 85, 
pl. 76, f. 694, 695; Turton, Biv., p. 229, pl. 18, f. 4, young. 
[Osrracka. 
Shell generally oblong, suboyal, compressed, and rough exter- 
nally, but not undulating; beaks terminal; under yalve thin, 
but not scaly; yellowish fawn-coloured externally, and rosy red 
Length nearly two inches; breadth one and a half. 
Young shells are somewhat triangular, with their sides ob- 
within. 
tusely cut down. 
Found by Dr. Turton, near Broadsands, Torbay, at the very 
lowest Spring tide. 
8. Anomia PpuncTATA, pl. XXXIX, f. 13. 
Anomia punctata, Gmelin, Syst., p. 3346; Chemnitz, VIII, 
p: 88, pl. 77, f. 698; Turton, Biv., p. 231, pl. 18, f. 11. 
Shell orbicular; beaks terminal; upper valve convex, covered 
with numerous raised dots; under valve flat, with small and 
numerous punctures;_ base somewhat truncated. Diameter 
about an inch. 
Found on crabs and shells, on the south coasts of England. 
9. ANomIA ForNicaTa, pl. XXXIX, f. 14, 15. 
Anomia fornicata, Lamarck, VI, pt. Ist, p. 228; Turton, 
Biv., p. 234, pl. 18, f. 12, 13. 
Shell dirty white, somewhat orbicular, compressed, finely 
striated; upper valve convex, provided with a vaulted chamber 
near the back; hinge pointed, and nearly terminal; sides near 
the margin irregularly sinous, with numerous, very fine, radi- 
ating striw, and with fine, regular, transverse strie near the 
hinge; under valve flat, with the perforation round, and nearly 
closed; inside of a silvery metallic lustre; margin provided 
with fine, longitudinal striae, the hollow vaulted chamber, which 
is considerably curyed on one side, and scaly externally. Dia- 
meter about half an inch. 
Found at Torbay. 
10. ANOMIA STRIOLATA. 
Anomia striolata, Turton, Biv., p. 233. 
Shell oval, somewhat cylindrically convex, and longitudinally 
striate, with recurved beaks. 
Dr. Turton says this shell resembles the A. cylindrica, in all 
respects, “but is always marked with fine, rather remote, longi- 
tudinal raised lines.” 
Found in the roots of Fuct. 
11. ANOMIA TUBULARIS. 
Anomia tubularis, Turton, Biv., p. 234. 
Shell cream-white, orbicular, with the perforation of the 
under valve entire all round, and forming a raised cylindrical 
tube; beak terminal; plug tendinous. 
Found attached to Fuci. 
The two latter shells are very doubtful species; they are 
given on the authority of Turton. 
Genus 4.—OsTrEA.—Linneus. 
Shell inequivalve, irregular, and foliacoous ; umbones some- 
what separated, and of unequal size; lower valve largest, con- 
cave, and frequently adherent ; upper valve smaller, and some- 
what plain; hinge destitute of teeth; ligament partly external ; 
the facet to which it is attached is subtrigonal, tripartite, and 
divided by two elevated lines, which divaricate from the umbo ; 
each valve provided with two muscular impressions, the one 
large, suborbicular, and nearly central, the other very small, and 
situate near the hinge. 
