MOLLUSCA. 
73 
Pectinides.] 
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 sindosus, 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; Ib., 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 sjnnosus, 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 
lamina; ; 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 differs in several respects, especially 
in the inequality of the auricles. The longitudinal striae 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 striae, 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, off 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 striae. The 
rays on the upper surface are furnished with short, broad, 
obtuse spines, crowning the convex flexure of the undulated 
striae ; the spines only exist towards the margin on the lower 
valve. The rugose appearance of the longitudinal striae 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 striae ; , 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 ais 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. 
T 
