400 
MOLLUSC A. ARCADJE. Pectunculus. 
upon the surface ; anterior margin straight, prominent near the hinge. — 
Sower. Min. Conch, t. ccvii. f. 2. — In Green Sand. 
6. C. elongata Elongated, subcylindrical, finely striated ; anteriorly 
pointed ; posterior side very short.— .S'ower. IMin. Conch, t. ccccxlvii. f. 1 — 
Inferior Oolite. 
7- C. costellata Transversely oblong, gibbose, longitudinally striated ; an- 
terior lobe wing-shaped, ribbed ; posterior side rounded, ribbed ; beaks in- 
curved, distant from each other.— *S'o^cer. Min. Conch, t. ccccxlvii. £ 2 . — Green 
Sand. 
8. C. minuta Elongated-ovate, convex, striated, anteriorly submucrona- 
ted ; anterior lobe small, separated by a keel ; beaks nearly close. — Soiver. 
Min. Conch, t. ccccxlvii. f. 3 — Oolite. 
9. C. rudis Transversely oblong, convex, rugged, and longitudinally rib- 
bed ; beaks incurved, nearly close together ; anterior lobe not defined. — 
Sower. Min. Conch, t. ccccxlvii. £ 4 — Oolite* 
Gen. XCIX. PEC TUNCULUS.— Shell orbicular, subequi- 
lateral ; hinge line semicircular, the teeth in the middle ob- 
solete ; ligament external. 
405. V.pilosus . — Shell tumid, nearly equilateral, with nu- 
merous longitudinal striae and transverse hnes of growth. 
P. ingens. List. Conch, t. ccxlvii. £ 82 — Area '’pilosa, Linn. Syst. i. 1 1 43. 
Area Glycymeris, Penn. Brit. Zool. iv. 98, t. Ivii. £ 58 — A. pilosa, 
Mont. Test. Brit. 137 — Pect. Glycymeris, pilosus, and undatus, TuH. 
Biv. Brit, 171 — Inhabits deep water. 
Diameter upwards of 2 inches, covered with a thick, brown, pilose cuticle, 
underneath which the shell is whitish, with brown interrupted stripes, either 
transverse or longitudinal ; beaks tumid, and slightly recurved ; inner mar- 
gin notched This species differs from the P. glycymeris of Lamark in the 
absence of the longitudinal ribs, with their intermediate striae. 
406. P. decussatus . — Shell orbicular, flat, decussate, with 
clouded coloured marks.” 
Tun. Biv. Brit. 173, t. xii. £ 5 — British Channel. 
“ Shell an inch in diameter, quite orbicular, flattish, with numerous fine 
raised decussate lines, which are clothed with a silky brown pile ; colour 
yellowish-white, with purple and crimson clouded patches, which are often 
disposed in zigzag angles, giving the shell a beautifully marked appearance r 
inside Fglossy white, with frequently a dark red blotch near the centre ; the 
margin very strongly serrate.” — Turton. 
407. P. nummarius . — Shell lenticular, with the beaks per- 
manent, covered with numerous rounded red dots.” 
P. exiguus. List. Conch, t. ccxxxix. f. 81. Turt. Biv. Brit. 174. t. xii. 
£ 6 — Torbay and British Channel. 
“ Shell about half an inch in diameter, rather convex, very finely decus- 
sate, yellowish white, or cream colour, with numerous round red dots, which 
very rarely become confluent about the margin, and form short lines ; beaks 
tumid and prominent, causing the margin on each side of them to appear a 
little projecting, or, as it were, slightly eared like a pecten.” — Turton. 
