394 
MOLLUSCA. OSTREADJ5. 
Anomia. 
** Valves plaited. 
17 . O. 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. fiabellula. — 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. Conch, t. cclv. 
. — In London Clay. 
21. O. mnwato.— Elongated, pointed at both ends, arched ; sides flattened ; 
middle longitudinally cariniformed ; plaits numerous, angular and regular ; 
ears two, variable. — My thus 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. — Falcilbrm depressed, with a large rectangular ear or 
wing within the curve ; margin deeply toothed ; one valve attached by a great 
jiart of its surface. Sower. Min. Conch, t. cccclxviii. f. 2, 3. — Iron Sand. 
24. O. cos/a/a.— 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. DIANCHORA. — Inequivalved ; the attached valve ha- 
ving an opening in place of a beak ; the other beaked and 
eared. 
1. D. sifna^a.— Oblique, ovate, triangular; beak prominent ; free valve ob- 
scurely ribbed. — Sower. Min. Conch, t. Ixxx. f 1 In Green Sand. 
2. D. lata — Semicircular ; beak rising ; free valve plain. — Sower. Min. 
Conch, t. Ixxx. f. 2. — Mant. Suss. 205. t. xxvi. f. 21 Podopsis striata, Cuv. 
Oss. Foss. ii. 319. t. v. f. 2 — In Chalk. 
3. D. ohliqua — Obliquely obovate ; upper valve convex, marked with nu- 
merous diverging striae ; margin serrated — Mant. Suss. 206. t. ^xv. f. L 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. electrica.-^^\\Q\\ somewhat orbicular, with the sur- 
face a little undulate, transparent, and amber colour. 
