MVARIA.] 



MOLLUSCA. 



Ill 



length, forming acute angles, their origin close to the cardinal 

 hiatus, with the inner limb continued by a rib similar to that 

 on the opposite valve. 



1. Lepton squamosum, pi. XL, f. 7- 



Psammobia punctura, First Ed., pi. 16, f. 7 ; Lepton squa- 

 mosum, Turton, Biv., p. 62, pi. 6, f. 1, 2, 3; Fleming, p. 

 429 ; Solen squamosits, Montagu, p. 565 ; Maton and Rackett, 

 p. 48. 



Shell compressed, a little transversely elongated ; both sides 

 equally rouuded ; pellucid, thin, and white ; whole surface 

 covered with minute and thickly studded punctures, having 

 much the appearance of shagreen when viewed through a 

 strong lens; inside smooth, glossy, white, with obscure, longitu- 

 dinal, radiating striae, diverging from the hinge. Length four- 

 tenths of an inch ; breadth half an inch. 



First met with in sand from Salcomb Bay; Turton mentions 

 Torbay ; and Mr. Lyons found it at Tenby. 



2. Lepton nitidum. 



Leplon nitidum, Turton, Biv., p. 63. 



" Shell glossy, slightly striate transversely. 



" Shell half the size of the last, which it resembles in shape 

 and hinge, but is of a lucid, pale, glossy horn-colour, without 

 punctures. 



"From corallines, in Torbay." — Turton. 



Genus 40 Myatella Brown. 



Shell thin, transversely oblong-ovate, inequilateral; hinge line 

 nearly parallel, truncated at one side; hinge with a large, single, 

 erect, spear-shaped tooth in one valve, resting upon a corres- 

 ponding cavity in the cardinal region of the other valve ; mar- 

 gins smooth and even. 



1. Myatella Montagui, pi. XL, f. 26, 27. 



Hiatella striata, First Ed., pi. 16, f. 26, 27; Myatella stri- 

 ata, Brown, Conch. Text Book, p. 142, pi. 16, f. 12 and 30; 

 Mya striata, Montagu, Linn. Trans., XI, p. 188, pi. 13, f. 1 a ; 

 Lyonsia striata, Turton, Biv., p. 35. 



Shell transversely elongated, thin, semitransparent; umbones 

 short, obtuse, and situated nearest the posterior or truncated 

 side, which is shortest ; anterior side rounded ; whole surface 

 covered with a very thin, olivaceous epidermis, beneath which 

 the shell is finely striated longitudinally, and is of a pearly hue; 

 inside smooth, pearlaceous, and exhibiting nacred reflections. 

 Length half an inch ; breadth an inch. 



Discovered in Tenbay-bay, by Mr. George Lyons. 



It is not without considerable hesitation that I have instituted 

 this genus, but I think it impossible that so accurate an observer 

 as Montagu could describe the tooth of this shell as fixed, if it 

 had not been so. Our figures are copied from his. Dr. Fle- 

 ming says he followed Turton in bringing together the syno- 

 nims, but with considerable hesitation. 



Genus 39 — Magdala Leach. 



Shell generally thin, transverse, inequivalve, inequilateral, 

 gaping at the anterior side ; hinge with a transverse, heart- 

 shaped, unattached plate-like tooth, to which both valves are 

 united by a small cavity on which this laminar plate is seated, 

 and fixed by a ligamentary process ; destitute of lateral teeth ; 

 ligament internal. 



1. Magdala striata, pi. XLIV, f. 1, 2, and 10. 



Magdala striata, First Ed., pi. 11, f. 1, 2, and 10; Mya 

 Norivegica, Wood, Cat., p. 1 1 ; Fleming, p. 463 ; Mya pellu- 

 cida, Brown, Wernerian Mem., II, p. 504, pi. 24, f. 1 ; Lyonsia 

 striata, Turton, Biv., p. 35, pi. 3, f. 6, 7. 



Shell thin, subpellucid, transversely oblong; hinge line nearly 

 parallel; anterior side shortest, and well rounded; posterior side 

 truncated, gaping, and with the edges reflected; from the base 

 of the truncation the shell abruptly obliques, until it reaches 

 the basal line; umbones not quite central, very obtuse, and 

 straight; surface covered with a thin, olivaceous epidermis, with 

 pretty strong, concentric wrinkles, which are more strongly 

 developed at the sides, especially the truncated one, where 

 they are rugose and sharp ; beneath the epidermis the shell 

 is thickly beset with fine, longitudinal, slightly waved striae, 

 which is less strong towards the disks of the valves; inside 

 of a rich pearlaceous hue, exhibiting iridescent reflections. 

 Length about five-eighths of an inch; breadth an inch and a 

 quarter. 



First discovered by Miss Hutchins, in Bantry Bay, Ireland, 

 has since been found at Warren Point; at Tenby, Wales; and 

 the Western coasts of England. 



Genus 41 Mya Linnaeus. 



Shell transverse, nearly equivalve, gaping at both extremities, 

 but widest at the posterior side ; one valve with a large, com- 

 pressed, dilated, hollow, spoon-shaped, perpendicular, vertically 

 projecting tooth ; the opposite valve destitute of teeth ; the 

 cartilage placed in a narrow suture ; two lateral, distant, large, 

 muscular impressions, the anterior one narrow, and the posterior 

 almost orbicular; pallial impression with a large sinus; ligament 

 internal, large, and fixed in the cavity of the tooth in one valve, 

 and to a large subumbonal cicatrix in the other. 



1. Mya arenaria, pi. XLV, f. 1. 



Mya arenaria, First Ed., pi. 10, f. 1; Montagu, p. 30; 

 Donovan, II, pi. 85 ; Lamarck, V, p. 461 ; Turton, Biv., p. 

 32 ; Fleming, p. 463. 



Shell strong, transversely oblong-oval, and moderately con- 

 vex ; umbones rather large, prominent, nearly central, and not 

 incurved ; one side more ample and rounded than the other. 

 which is somewhat acuminated, and pointed at the extremity ; 

 external surface generally with concentric wrinkles and irregular 

 striae, mostly of a brownish sand-colour, but differing considera- 

 bly from various localities, as well as from the age of the shell ; 

 one valve with a broad, thick, perpendicular tooth, provided 

 with a large spoon-like cavity for the reception of the cartilage, 

 and another smaller one by its side ; opposite valve destitute of 

 teeth ; inside glossy, white. 



Inhabits many of the British and Irish coasts, particularly at 

 the mouths of rivers. 



2. Mya truncata, pi. XLV, f. 2. 



Mya truncata, First Ed., pi. 10, f. 2; Montagu, p. 32; Dono- 

 van, III, pi. 92; Maton and Rackett, p. 35; Turton, Biv., p. 

 31 ; Forbes, p. 54. 



