Pectinides.] 



MOLLUSCA. 



73 



Found at Anglesey, by Pennant ; Montagu met with it at 

 Falmouth and Salcomb Bay, Devonshire ; and I found it on the 

 Durham coast. 



It is doubtful whether this is not a mere variety of P. obso- 

 letus, in the young condition. 



10. Pecten sinuosus, pi. XXV, f. 2. 



Pecten sinuosus, First Ed., pi. 32, f. 2 ; Fleming, p. 384 ; 

 Lamarck, IV, p. 175; Turton, Biv., p. 210, pi. 9, f- 5; Forbes, 

 p. 40 ; Ostrea sinuosa, Maton and Rackett, p. 99 ; Brown, 

 Wernerian Mem., p. 514; lb., Ency. Brit., p. 418; Ostrea 

 pusio, Pennant, p. 101, pi. 41, f. 65 ; Donovan, pi. 34. 



Shell ovate, with numerous, divergent ribs, of unequal thick- 

 ness ; under valve convex, adherent, and much distorted, from 

 its partaking of the form of the substance to which it adheres, 

 by which the whole of the ribs are, in general, obliterated, 

 except towards the umbo ; upper valve more flat than the 

 inferior, and more or less sinuous like the opposite valve ; its 

 whole surface is covered with foliated, spinous, or scaly ribs, 

 but these are interrupted by the transverse swellings and 

 depressions which traverse it, these distortions frequently giving 

 an undulated appearance to the ribs ; auricles large, in many 

 specimens nearly equal, in others they are small and irregular ; 

 colour variable, sometimes reddish-brown, orange, or yellow, 

 and other specimens are mottled and clouded with white. 

 Length two inches ; breadth an inch and a half. 



Found on many of the English and Irish coasts. 



11. Pecten spinosus, pi. XXIV, f. 8. 



Pecten spinosus, First Ed., pi. 33, f. 8 ; Pecten pusio, Tur- 

 ton, Biv., p. 215, pi. 17, f. 2; Fleming, p. 385; Hinnites pusio, 

 Sowerby, Zool. Journ., Ill, p. 71. 



Shell oblong-ovate, with about forty-two alternately higher 

 and lower ribs, thickly set with vaulted spines, and longitudi- 

 nally striated ; ears very unequal in size, and obliquely ribbed 

 and spinous ; beneath the superior ear are five tooth-like 

 laminae; upper valve less convex than the lower; colour various, 

 being plain yellow, orange, or brown, and sometimes clouded 

 with brown or chocolate-colour. Length three and a half 

 eighths of an inch ; breadth somewhat more than two and a 

 half eighths. 



I first found this on the Herd Sands, at South Shields ; 

 W. C. Trevelyan, Esq., met with it at Seaton. It also occurs 

 at Eyemouth, Berwickshire ; and was found at Torbay, by 

 Turton. 



This species has much the aspect of the young of P. varius, 

 but will at once be distinguished by its more elongated form, 

 and in the ribs being alternately higher and lower. 



12. Pecten Jamesoni, pi. XXV, f. 7. 



Pecten Jamesoni, Forbes, Wernerian Mem., VIII, p. 58, pi. 

 2, f. 1. 



Shell subequivalve, suborbicular, with longitudinal, undulated 

 plaits, striated ; the plaits four or five ; ears unequal. Length 

 and breadth three-quarters of an inch. 



"Allied to the Pecten polymorphus of Bronn (Phillippi, p. 

 79, tab. V, f. 18, 21), but diners in several respects, especially 

 in the inequality of the auricles. The longitudinal stria; vary 

 much in coarseness ; the upper valve is somewhat larger than 

 the lower ; the auricles are ribbed and striated by lines of 

 growth ; the longitudinal ribs or folds vary much in convexity, 



and are sometimes acutely carinated. The colour is white, 

 with a tinge of red, especially near the beaks. Very distinct 

 from any recorded British species." — Forbes. 



Dredged at Bute, by James Smith, Esq., of Jordan Hill. 



13. Pecten Landsburgi. 



Pecten Landsburgi, Forbes, Wernerian Mem., VIII, p. 58, 

 pi. 2, f. 2. 



Shell subequivalve, suborbicular, radiated with very small, 

 longitudinal, rugose stria;, and crossed by regular, undulating, 

 transverse striae ; auricles unequal. Length half an inch ; 

 breadth five-twelfths. 



"A very beautiful species, allied to Pecten obsoletus, first 

 observed by the Rev. Mr. Landsborough, on the coast of Ayr- 

 shire, afterwards dredged by Mr. Smith, oft" the coast of Bute. 

 In colour it resembles Pecten obsoletus, but is somewhat more 

 triangular in form ; from that species, however, it is easily dis- 

 tinguished by the lineations of its surface, which is adorned by 

 numerous regular minute rays rugosely striated, and crossed by 

 regular undulated transverse, somewhat distant stria;. The 

 rays on the upper surface are furnished with short, broad, 

 obtuse spines, crowning the convex flexure of the undulated 

 stria; ; the spines only exist towards the margin on the lower 

 valve. The rugose appearance of the longitudinal stria; is 

 caused by the interstices being punctate." — Forbes. 



14. Pecten glaber, pi. XXV, f. 3, 4. 



Pecten glaber, First Ed., pi. 32, f. 3, 4 ; Pennant, IV, p. 102. 

 No. 68 ; Montagu, Sup., p. 59, pi. 28, f. 6 ; Fleming, p. 384. 



Shell rather compressed, nearly smooth, with extremely 

 minute, concentric striae, visible only by the aid of a strong 

 lens; with seven nearly obsolete, rounded ribs, and interme- 

 diate longitudinal stria; ; surface mottled with reddish-brown 

 and yellow, sometimes plain ; ears large, nearly equal, the one 

 reticulated, the other only striated ; inside with twenty-one 

 slender rays, the sixteen middle ones arranged in fours, the 

 two middle series approximating, filling the intervening hollows 

 between the outer sulci ; inside same colour as the outside, but 

 paler, except near the hinge. Length three-quarters of an 

 inch ; breadth somewhat less. 



Found at Anglesey, by Pennant, and in the Frith of Forth, 

 at Dunbar, by Captain Laskey. 



15. Pecten similis, pi. XXV, f. 5, 6. 



Pecten similis, First Ed., pi. 32, f. 5, 6 ; Laskey, Wernerian 

 Mem., I, p. 387, pi. 8, f. 8 ; Fleming, p. 385. 



Shell subcompressed, thin, smooth, semitransparent, clouded 

 with brown; ears unequal; under side more prominent than 

 the upper. 



Found in the Frith of Forth, by Captain Laskey. 



16. Pecten tumidus. 



Pecten tumidus, Turton, Biv., p. 212, pi. 17, f. 3; Fleming, 

 p. 384. 



"Shell equivalve, inequilateral, quite smooth, with one of the 

 sides produced ; a quarter of an inch in diameter, orbicular, 

 glossy white, transparent, and without striae, ribs, or marks of 

 any kind ; the sides not equal, in consequence of one of them 

 being prominent in a rounded manner; ears nearly equal." — 

 Turton. 



Taken from the Serpula tabularia, at Torbay, by Dr. 

 Turton. 



