LlTHOPHAGI.] 



MOLLUSCA. 



103 



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. 



Psammobia Laskeyi, Turton, Biv., p. 89 ; Fleming, p. 438 ; 

 Tellina Laskei/i, 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 crenulae ; 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, which 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, and prcecisa, 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 ; 3fytilus rugosus, Pennant, IV, p. 110, pi. 63, 

 f. 72; Montagu, p. 164; Donovan, pi. 141 ; Maton and Rackett, 

 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. XLVIII, is the variety Mylilus pracisus, Mon- 

 tagu, p. 165, pi. 4, f. 2 ; Maton and Rackett, 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 alga, 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. 1 1 ; and fig. 14 a still more globular 

 form of the same species. 



2. Saxicava purpurea, pi. XLII, f. 29, 30, 31. 



Mi/a 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 stria? ; 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 ininutus, First Ed., pi. 13, f. 1 ; Lamarck, V, p. 453 ; 

 Montagu, p. 53, pi. 1, f. 4; Maton and Rackett, p. 47; Hiatella 

 minuta, Turton, Biv., p. 24; Hiatella arctica, 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 oblonga, Turton, Biv., p. 25, pi. 2, f. 13 ; Hiatella 

 arctica, Fleming, p. 461. 



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; 



