^94 MOLLUSCA. OSTREAD^. Anomia. 



** Valves plaited. 



17. O. Marshii.— Oblique, both valves deeply plaited in seven or eight an- 

 gular diverging undulations ; edge thick, flatted — Sower. Min. Conch, t. xlviii. 

 — Lower Oolite. 



18. O. gregaria Clustered, oblong, curved, plaited ; plaits many, rugged, 



diverging from a longitudinal plait or sulcus ; valves unequally convex ; 

 beaks produced and curved, — Sower, t. cxl. f. 1, 3. — Lower Oolite. 



19. O. palmetta. — Ovate, roundish, obscurely one-eared, depressed, with a 

 plaited margin ; plaits diverging from a longitudinal space ; beaks straight — 

 Sower. Min. Conch, t. cxl. f. 2 — Lower Oolite. 



20. O. flabelhda. — Oblong, arched ; larger valve deep, longitudinally stria- 

 ted, with a toothed margin ; the other flat and imbricated, with an entire 

 margin. (Chama plicata, Brand. Foss. f. 84, 85.) Sower. Min. Couch, t. eclv. 

 — In London Clay. 



21. O. carinata.— Elongated, pointed at both ends, arched ; sides flattened ; 

 middle longitudinally cariiiiformed ; plaits numerous, angular and regular ; 

 ears two, variable — Mytilus Crista Galli, White, Selb. i. 12. O. car. Sower. 

 Min. Conch, t. ccclxv. — In Green Sand. 



22. O. solitaria. — Obovate ; one valve flattish ; plaits deep, sharp, rugged, 

 and branched; beaks short. — Sower. Min. Conch, t. cccclxviii. f. 1. — Found 

 near Weymouth. 



23. O. macroptera. — Falciform depressed, with a large rectangular ear or 

 wing within the curve ; margin deeply toothed ; one valve attached by a great 

 part of its surface. Soiver. Min. Conch, t. cccclxviii. f. 2, 3. — Iron Sand. 



24. O. costata Orbicular ; lower valve deep, ribbed ; ribs numerous, 



branched ; upper valve flat, with an undulated margin — Sower. Min. Conch. 

 t. cccclxviii. f. 3 — In Oolite. 



Gen. DIANCHOIt A. — Inequivalved ; the attached valve ha- 

 ving an opening in place of a beak ; the other beaked and 

 eared. 



1. D. striata. — Oblique, ovate, triangular; beak prominent ; free valve ob- 

 scurely ribbed — Sower. Min. Conch, t. lxxx. f. 1 — In Green Sand. 



2. D. lata — Semicircular ; beak rising ; free valve plain. — Sower. Min. 

 Conch, t. lxxx. f. 2 — Mant. Suss. 205. t. xxvi. f. 21. — Podopsis striata, Cuv. 

 Oss. Foss. ii. 319. t. v. f. 2 — In Chalk. 



3. D. obliqua — Obliquely obovate ; upper valve convex, marked with nu- 

 merous diverging striae ; margin serrated — Mant. Suss. 206. t. xxv. f. 1. t. 

 xxvi. f. 12. — In Chalk. 



Gen. XCVII. ANOMIA. — Inequivalve, irregular; under 



valve with a notch or perforation near the beak, for the 



passage of the tendon, by which the shell adheres to foreign 



bodies ; ligament internal, placed transversely under the 



beak. 



— 389- A. cleclnca. — Shell somewhat orbicular, with the sur- 

 face a little undulate, transparent, and amber colour. 



