400 MOLLUSCA. ARCADiE. 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. — Smver. Min. Conch, t. ccccxlvii. f. 1 — 



Inferior Oolite. 



7. C. costellata Transversely oblong, gibbose, longitudinally striated ; an- 



tei'ior lobe wing-shaped, ribbed ; posterior side rounded, ribbed ; beaks in- 

 curved, distant from each other — Sotcer. Min. Conch, t. ccccxlvii. £ 2.— Green 

 Sand. 



8. C. minuta Elongated-ovate, convex, striated, anteriorly submucrona- 



ted ; anterior lobe small, separated by a iceel ; beaks nearly close — Soicer. 

 Min. Conch, t. ccccxlvii. f. 3. — Oolite. 



9. C. rridis Transversely oblong, convex, rugged, and longitudinally rib- 

 bed ; beaks incurved, nearly close together ; anterior lobe not defined — ■ 

 Sower. Min. Conch, t. ccccxlvii. f. 4 — Oolite. 



Gen. XCIX. PECTUNCULUS.— Shell orbicular, siibequi- 

 lateral ; hinge line semicircular, the teeth in the middle ob- 

 solete ; ligament external. 



4<05. Y.pilosus. — Shell tumid, nearly equilateral, Avith nu- 

 merous longitudinal striae and transverse lines of growth. 



P. ingens. List. Conch, t. ccxlvii. f. 82 — Area '^pilosa, Linn. S^'st. i. 1 1 43. 

 Area Glycymeris, Penn. Brit. Zool. iv. 98, t. Ivii. f. 58 — A. pilosa, 

 Mont. Test. Brit. 137 — Pect. Glycymeris, pilosus, and undatus, Turt. 



Biv. Brit. I7I 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 sfightly 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.'" 



Turt. Biv. Brit. 173, t. xii. f. 5 — British Channel. 

 " Shell an inch in diameter, quite orbicular, fiattish, witii numerous fine 

 raised decussate lines, which are clothed with a silky brown pile ; colour 

 yeUowish-white, with purple and crimson clouded patches, which are often 

 disposed in zigzag angles, giving the shell a beautifully marked appearance : 

 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. 

 f. 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 a'nd prominent, causing the margin on each side of them to appeal* a 

 little projecting, or, as it were, slightly eared like a pecten." — Turton. 



