MOLLUSCA. 
103 
Lithophagi.] 
smaller being, however, a little stronger ; inside yellowish or 
cream-white, with numerous, glossy, circular spots ; pallial im- 
pression with a large sinus, placed transversely, but does not 
interrupt the pallial impression below’, as it rises at the acumi- 
nated side. 
Found in Bantry Bay, Killough, County of Down, and other 
places on the coast of Ireland. 
7. PSAMMOBIA Laskeyi, pi. XXXIX, f. 32. 
Psammohia LasTceyi, Turton, Biv., p. 89; Fleming, p. 438; 
Tellina Laskeyi, Montagu, Sup., p. 28, pi. 28, f. 3. 
Shell transversely oblong-ovate, smooth, rather strong ; um- 
bones not quite central, and obtuse, hardly inflected ; sides dis- 
similar, one rounded, the other obtusely pointed and obliquely 
subtruncated ; colour purplish-white ; covered with an olivace- 
ous-yellow epidermis ; inside purple, smooth, white round the 
margin, and destitute of the crenulse ; one valve with three 
approximate, subbifid teeth ; the margin channelled from the 
teeth almost to the end of the longer side ; on the other 
side of the teeth the margin is replicated, or folded back to 
the connecting cartilage, to which it is affixed ; the opposite 
valve with only a single tooth, which locks in between the 
teeth of the other valve, these are reciprocally admitted into 
a cavity on each side in this valve, wliich is destitute of a 
channel on the margin. Length half an inch; breadth three- 
quarters. 
Discovered, by dredging, in the Frith of Forth, by Captain 
Laskey. 
Family V. — Lithophagi. 
Shells which bore into clay, wood, and other substances; des- 
titute of accessory pieces ; more or less gaping at the anterior 
side ; ligament situate exteriorly. 
Genus 26. — Saxicava. — Lamarck. 
Shell transverse, irregular in form, generally oblong, inequi- 
lateral, subequivalve, gaping anteriorly ; ligament exterior ; two 
lateral, muscular impressions in each valve ; pallial impression 
interrupted, but not sinuated ; hinge, in the young condition, 
with sometimes two or three minute, obtuse, mostly indistinct, 
cardinal teeth, which become obsolete in the adult ; two deep 
muscular impressions in each valve ; pallial impression entire. 
1. Saxicava rugosa, pi. XLVII, f. 14 and 16, and pi. 
XL VIII, f. 15, 16. 
Pholabia rugosa, First Ed., pi. 9, f. 15, Bind prcBcisa, f. 16; 
Leach, MSS., p. 5; Saxicava rugosa, Lamarck, V, p. 501; 
Turton, Biv., p. 20, pi. 2, f. 10; Forbes, p. 56; Hiatella rugosa, 
Fleming, p. 461 ; Blytilus rugosus. Pennant, I V, p. 1 10, pi. 63, 
f. 72; Montagu, p. 164; Donovan, pi. 141; Maton and Racket!, 
p. 105. 
Shell transversely oblong-ovate, somewhat inflated ; and 
gaping at one side ; umbones small, obtuse, and situate near to 
the anterior side ; posterior side always rounded ; anterior side 
generally subtruncated ; surface brown or dull yellowish-white, 
with irregular, rugged, concentric wrinkles ; inside white. 
Fig. 16, pi. XL VIII, is the variety Mytilus prcvcisus, Mon- 
tagu, p. 165, pi. 4, f. 2; Maton and Racket!, p. 105. 
This species is liable to great variety in its external form, as 
will be seen by our various figures, being sometimes subquad- 
rangular or subcylindrical, frequently much distorted and wrin- 
kled, at others almost smooth. It is a frequent inhabitant of 
the roots of the large algce, and even penetrates the hardest 
limestone ; it is met with on almost all the coasts of Britain 
and Ireland. 
Fig. 16, pi. XLVII, is the variety called Saxicava Pholadis, 
Turton, Biv., p. 21, pi. 2, f. 11; and fig. 14 a still more globular 
form of the same species. 
2. Saxicava purpurea, pi. XLII, f. 29, 30, 31. 
Mya purpurea, Montagu, Sup., p. 21 ; Agina purpurea, 
Turton, Biv., p. 54, pi. 4, f. 9. 
Shell transversely oblong-ovate; umbones purple, placed con- 
siderably to one side, and inflected towards the shorter end, 
which is rounded ; the anterior end obliquely truncated; invested 
with a glossy, cream-white epidermis ; under which the shell is 
pure white, and covered with irregular, transverse striae ; hinge 
with a single, obscure, erect tooth in each valve, and slightly 
cleft, which penetrate cavities in the opposite valve. Length 
about an eighth of an inch ; breadth a quarter. 
Taken in deep water, amongst corallines, on the Devonshire 
coast, by Colonel Montagu ; and dredged at Torbay, by Dr. 
Turton. 
Genus 27 Hiatella Daudin. 
Shell transverse, inequivalve, inequilateral, gaping at the 
superior margin, or anterior side ; umbones small, blunted, 
placed considerably towards the posterior side ; ligament exter- 
nal ; hinge with a small, ill defined, single tooth in one valve, 
inserted between two obscure ones in the other ; destitute of 
lateral teeth ; two large and deep muscular impressions in each 
valve, those on the anterior sides largest, with a tongue-like 
prolongation from the side, pointing inwards ; pallial impression 
entire. 
1. Hiatella minuta, pi. XLVII, f. 1. 
Solen minutus. First Ed., pi. 13, f. 1 ; Lamarck, V, p. 453 ; 
Montagu, p. 53, pi. 1, f. 4; Maton and Racket!, p. 47 ; Hiatella 
minuta, Turton, Biv., p. 24; Hiatella ay'ctica, Fleming, p. 461 ; 
Saxicava rugosa, young shell, Forbes; Coramya spinosa, Leach, 
MSS., p. 5. 
Shell transversely subovate, rugose, slightly inflated ; umbones 
placed towards the posterior side, which is rounded ; anterior 
side subtruncated ; one valve smaller than the other, each pro- 
vided with two rows of concave spines, situate on the anterior 
side, emanating from the umbones, and terminating on the side, 
the superior row running parallel with the cartilage line, the 
other running diagonally downwards; under valve projecting 
slightly over the other, except at the shorter side ; surface of a 
pale brown, or yellowish-white ; inside smooth, glossy, white, 
sometimes tinged with ochre-yellow. 
Found on most of the British and Irish coasts, burrowing in 
hard limestone rocks, clay, and other substances. 
2. Hiatella oblonga, pi. XLVII, f. 14. 
Hiatella ohlonga, Turton, Biv., p. 25, pi. 2, f. 13; Hiatella 
arctica, Fleming, p. 46 1. 
Shell transversely oblong-ovate; posterior side rounded; an- 
terior side subtruncated, slightly wrinkled transversely, rather 
prominent, and destitute of spines ; umbones placed near the 
posterior side ; surface of a pale brown, or yellowish-brown ; 
