384 MOLLUSCA. BIVALVIA. Pecten. 
375. P. sinuosus. — Distorted with numerous foliated or spi- 
nous rays. 
P. minimus, angustior, List. An. Ang. 186. Conch, t. clxxii. and clxxxix. 
— Wallme^ Ork. 44.— P. Pusio, Penn. Brit. Zool. iv. 101. t. Ixi. f. 65. 
P. distortus, Mont. Test. Brit. 148. — P. sinuosus, Turt. Biv. Brit. 210. 
—tin crevices of sea rocks. 
Length seldom two inches, and breadth an inch and a half ; colour various ; 
lower valve convex, the left nearly flat, especially towards the extremity ; 
ribs numerous, unequal, and covered with foliaceous spines along the layers 
of growth. This species, when lodging in the crevices of rocks, is apt, like 
the Mytili., to become distorted by confinement ; a circumstance which has led 
some naturalists to believe (though they admit the existence of a hyssus^ 
that the shell is attached by its lamellar spines, to the rock ; and that it be- 
longs to the genus Hinnites of Be France. 
376. P. gldber. — Shell with seven obsolete ribs and interme- 
diate longitudinal stri^, nearly smooth. 
Penn. Brit. Zool. iv. 102. Mont. Test. Brit. Sup. 59. t. xxviii. f. 6. — 
Anglesea and Firth of Forth, rare. 
Length and breadth about an inch, mottled with brown and yellow, or 
plain ; the largest ear reticulated, the other striated ; the valves are rather 
flat ; minutely striated concentrically by the layers of growth ; inside with 
21 slender rays, the middle ones in fours. 
377. P. tumidus. — “ Shell equivalve, inequilateral, quite 
smooth, with one of the sides produced.” 
Turt. Biv. Brit. 212. t. xvii. f. 3. — Taken fix>m the Serpula tubularia, in 
Torbay. 
“ Shell a quarter of an inch in diameter, orbicular ; glossy white, transpa- 
rent, and without striae, ribs, or marks of any kind ; the sides are not equal, 
in consequence of one of them being prominent in a rounded manner ; ears 
very nearly equal.” 
Ears of the shell unequal. 
378. P. Ribs thirty-two, rounded, with numerous 
scaly spines. 
P. subrufus. List. Conch, t. 180. — Ostria var. Linn. Syst. i. 1146 — Pec- 
ten var. Penn. Brit. Zool. iv. 101. t. Ixi. f. 64. Mmt. Test. Brit. l46. 
Turt. Biv. Brit. 214. — On oyster beds. 
Length upwards of two inches ; white, red, or mottled ; spinous scales con- 
cave on the layers of growth ; furrows finely reticulated. 
379. P. niveus. — Ribs forty-two, rounded, with few scaly 
spines. 
Macgillivray^ Edin. Phil. Journ. vol. xiii. 166. t. iii. f. 1.— From the 
outer Hebrides. 
This species differs from the preceding in the pure whiteness of its colour ; 
the greater number of its ribs, with their few scaly spines, and in the fur- 
rows being marked with transverse waved striae, instead of reticulations. I 
owe the specimen in my possession to the kind attention of Mr Macgilli- 
vray. 
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