334 0STREA1M-. 



A. patelliformis, Linnaeus. 



Surface radiated with regularly disposed wavy ribs ; a trian- 

 gular cavity on the under valve beneath the hinge. 



Plate LVI. fig. 5, 6. 



Anomia Patelliformis, Linn, (not Chemn.) Syst. Nat. ed. 12, p. 1151; Nov. 

 Act. Upsal. 1773, vol. i. p. 42, pi. 5, f. 6, 7.— Retzius, 

 Nova Genera Test. p. 11. — Loven, Moll. Scandinav. 

 p. 30. 

 Ostreum striatum, Da Costa, Brit. Conch, p. 102, pi. 11, f. 4. 

 Anomia undulaUm striata, 8[c., Chemn. Conch. Cab. vol. viii. p. 88, pi. 77, f. O'OD- 

 „ undulata, Gmelin, Syst. Nat. p. 3346. — Mont. Test. Brit. p. 157, pi. 

 4, f. 6. — Maton and Rack. Trans. Linn. Soc. vol. viii. p. 

 103. — Rack. Dorset Catalog, p. 39, pi. 11, f. 4. — Turt. 

 Conch. Diction, p. 4 ; Dithyra Brit. p. 230, pi. 18, f. 8, 9, 

 10. — Fleming, Brit. Anim. p. 395. — Macgilliv. Moll. 

 Aberd. p. 231. — Brit. Marine Conch, p. 122. — Brown, 

 Illust. Conch. G. B. p. 69, pi. 22, f. 2, 3. — Brugiere, 

 Encycl. Meth. vol. i. p. 74, pi. 171, f. 16, 17, and pi. 184, 

 f. 5, 6. — Dillw. Recent Shells, vol. i. p. 289. — Index Tea- 

 taceolog. pi. 11, f. 9. — Brown, Conch. Text-book, ed. 1, 

 p. 110. 

 Ostrea striata, Pulteney, Ilutchins, Hist. Dorset, p. 36. — Donov. Brit. Shells, 

 vol. ii. pi. 45.— Mont. Test. Brit. pp. 153, 580. 



The characters by which this apparently distinct form 

 may be discriminated from ephippium, are few in number, 

 but easy of observation. About twenty or thirty slightly 

 flexuous radiating ribs emanate from the umbonal region 

 (they are seldom if ever visible upon the umbo itself) of 

 the upper valve, and thence diverging all round, crenate 

 the outer margin of the shell. These are but moderately 

 elevated, convex (not square) above, and are for the most 

 part rather narrower than their interstices, which, as well 

 as themselves, are crowdedly traversed in a concentric 

 direction by very delicate and somewhat laminar stria?. A 

 rather narrow perpendicular dull-surfaced triangular area is 

 excavated, in a somewhat shelving fashion, in that portion 



