104 
MOLLUSCA. 
[CORBULACEA. 
hinge with an obscure, conic tooth in one valve, and a cavity 
for its reception in the other, with an obscure, nearly obsolete 
tooth on each side of it. 
This is so nearly allied to H. minuta, that we should have 
considered it a mere variety, but the total want of spines inclines 
us to think that it may be distinct. The figure we have given 
is from a specimen recently taken alive at Dunbar; Turton 
gives as its locality Torbay and Dublin Bay. 
Genus 28. — Sphenia. — Turton. 
Shell transverse, inequivalve, inequilateral, general form flat- 
tish wedge-shaped, gaping at the anterior end; hinge of the left 
valve with an elevated, transversely dilated tooth, that of the 
right valve with a concave tooth, and small denticle behind it ; 
destitute of lateral teeth ; two small muscular impressions in 
each valve ; pallial impression with a large tongue-shaped sinus, 
emanating from the anterior side, and reaching nearly the mid- 
dle of the valves ; ligament external. 
1. Sphenia Binghami, pi. XLII, f. 17, 18, and 22. 
Sphenia Binghami, First Ed., pi. 14, f. 16, 17, 18; Turton, 
Biv., p. 36, pi. 3, f. 4, 5, and pi. 19, f. 3 ; Fleming, p. 465. 
Shell transversely oblong-ovate, subcompressed, wedge-shaped, 
truncated at the hinge, with the superior margin frequently a 
little contracted about the middle, gradually tapering towards 
the anterior end, which is slightly gaping, and subtruncate; um- 
bones rather prominent, with their beaks not quite opposite, but 
divaricating from each other ; whole surface covered with a 
brown, wrinkled epidermis, which extends beyond the anterior 
side ; inside glossy, white, with a purplish tint ; the margin plain, 
and sharp ; the elevated tooth gradually diminishing, and ex- 
tending nearly half way along the hinge line. Length a quarter 
of an inch ; breadth half an inch. 
Found among the rocks at Torbay, by Dr. Turton and Gen. 
Bingham, after whom it was named by the doctor. 
2. Sphenia Swainsoni, pi. XLII, f. 16, 23, 24. 
Sphenia Swainsoni, Turton, Biv., p. 37, ph 3, f. 3, and pi. 
19, f. 2. 
Shell transversely oblong-oval, wedge-shaped; the anterior 
side round; umbones nearly central; a concave tooth, lying hori- 
zontally, and pointing inwards. Length a quarter of an inch ; 
breadth about half an inch. 
This species is somewhat more oval in its form than the S. 
Binghami. 
Found among the rocks at Torbay. 
3. Sphenia decussata, pi. XLV, f. 3. 
Mya decussata. First Ed., pi. 10, f. 3; Montagu, Sup., p. 20, 
pi. 28, f. 1; Fleming, p. 463; Sphenia decussata, Turton, Biv., 
p. 38. 
Shell suborbicular, slightly inflated ; umbones obtuse, re- 
curved, and situate nearest the posterior side; colour yellowish- 
white, crossed by rather remote, concentric ridges, which are 
decussated by strong, regular, longitudinal striaj, forming tuber- 
cles at the anterior end ; inside smooth, white ; in one valve a 
broad, erect tooth ; in the other a projecting lamina, with a 
small pit for the reception of the tooth in the opposite valve. 
Length not quite half an inch ; breadth somewhat more. 
Found in the Frith of Forth, by Captain Laskey. 
Family VI. — Corbdlacea. 
Shell inequivalve, and for the most part one valve somewhat 
larger than the other ; ligament placed interiorly. 
Genus 29* — Pandora. — Bruguiere. 
Shell free, thin, internally pearlaceous, inequivalve, trans- 
verse, inequilateral ; the anterior side the longer, subrostrated, 
and slightly gaping at its extremity; one valve flat, with two 
internal, anterior ribs, and with its anterior margin turned 
downwards, provided 'with a single, oblong, obtuse, cardinal or 
hinge tooth, situate behind the ligament ; the opposite valve 
concave, and destitute of teeth, but furnished with an indistinct 
cicatrice, on which the tooth of the flat valve rests, when the 
shell is closed ; in each valve are two distant, lateral, muscular 
impressions; ligament internal, its sides lodged in, and attached 
to an elongated cicatrice, which lies inclined to the anterior side 
of the valves ; in some species the cicatrix is produced into an 
elongated, divergent lamina, stretching from the umbo towards 
the anterior side of the shell, and terminating near the inner 
side of the anterior muscular impression. 
1. Pandora rostbata, pi. XL VII, f. 5, 12, 13. 
Ttnitina solenoides. First Ed., pi. 13, f. 5 ; Pandora marga- 
ritacea, Turton, Biv., p. 40, pi. 3, f. 11, 12, 13, 14; Pandora 
incequivalvis, Fleming, p. 466 ; Solen pinna, Montagu, p. 566 ; 
Tellina inequivalvis, Montagu, p. 71 ; Ib., Sup., p. 27 ; Dono- 
van, II, pi. 41, f. 1 ; Maton and Rackett, p. 50. 
Shell transversely oblong and subovate, thin, and brittle; one 
valve nearly flat, the other moderately convex ; the hinge line 
of both valves arcuated ; umbones placed much to one side ; 
posterior side extending into a lengthened, obtusely subtrun- 
cated beak ; the other side short, and rounded ; surface cream- 
white, with a pearly gloss, smooth in some specimens, but 
transversely wrinkled in others ; two teeth in both valves, but 
destitute of lateral ones; inside white, and slightly nacred; each 
valve provided with a blunt tooth, running parallel from the 
umbo, that in the convex valve largest, and with an uneven 
surface, these not inserted, but stand by the side of each other, 
when the valves are closed. Length nearly half an inch ; 
breadth one inch ; but sometimes considerably more. 
This species inhabits the sea at Dawlish, Guernsey ; and in 
several places on the Irish coast. 
Genus 30. — Corbula. — Bruguiere. 
Shell inequivalve, one valve being generally small and flat- 
tened, the other large and convex; subequilateral, transverse, 
generally gibbose and close ; each valve usually furnished with 
a single, conical, recurved, ascending, pointed tooth, at the side 
of which is a small concave depression, — very deep in some 
species, which serves either for the reception of the ligament, 
or the tooth of the opposite valve ; two distant, lateral, some- 
what irregular, muscular impressions in each valve ; pallial 
impression posteriorly angulated, with a very small sinus ; 
ligament internal, fixed to the tooth of the lesser valve, and 
inserted in the depression by the side of the tooth, in the 
larger valve. 
