PLATE LYII. 
1. Ostrea Bellovacina. ( Belovian Oyster.) Oblong, irregular, thick; lower valve convex, 
with sub-imbricated laminae; beak produced, straight ; ligamental area elevated above surface of 
shell ; hollow valve curved, acute, with deep canal in centre. 
2, 3. 0. Acuminata. {Acuminated Oyster.) Elongated, depressed, incurved; upper valve 
concave, smooth; with ears and acute nmbones; base acuminated; surface, with sub-imbricated, 
transverse lamina}. 
4. 0. Gigantea. ( Gigantic Oyster.) Elongated, thick ; umbo short; hinge-pit large, tripartite, 
with its sides flat, striated. 
5, 6, 7, 8. Anomia Lineata. (. Lineated Anomia.) Sub-orbicular, convex ; with many, fine, 
radiating strife. Fig. 8, adult stage. 
9. 0. Canaliculata. {Canalled Oyster.) Depressed, elongated, curved, slightly eared; sides 
parallel ; with a few, concentric lamina; near beak, and two or more, canaliculated projections in 
lower valve; upper valve flat. 
10. 0. Gregaria. {Gregarious Oyster.) Clustered, oblong, curved; beaks long; hinge-pit, with 
central cavity in lower valve ; one valve deeper than the other; surface, with broken, longitudinal 
plait, whence many, furcated ribs, crossed by imbricated laminae. 
11. 12. 0. Flabellula. {Little Fan Oyster.) Oblong, sub-arcuated; beaks prominent; larger 
valve deep, longitudinally curved and plaited with dentated margin; smaller valve flat, smooth ; 
margin plain ; with lateral crenulations. 
13. 0. Lseviuscula. {Very Smooth Oyster.) Depressed, rounded ; beak sub-acute, retroflected; 
scales distant; surface smooth, obscurely imbricated ; lower valve without ribs. 
14. 0. Tenera. {Tender Oyster.) Elongated, curved, thin, depressed; beak of upper valve 
acute, canaliculated ; surface plain, smooth, with imbricated lamina;. 
15. 0. Edlllina. {Smaller Edible Oyster.) Sub-orbicular, thickisli ; lower valve convex, with 
undulating laminae ; upper valve smooth, depressed ; beak curved, pointed. 
16. A. Squamula. {Scaled Anomia.) Sub-orbicular, very thin, flat; with indistinct, concentric 
wrinkles. 
17. A. Aculiata. {Spined Anomia.) Orbicular, compressed, with many, divergent stria;, sur¬ 
mounted by concave, obtuse spines ; umbones small ; under valve flat, smooth. Diameter, ■§■ in. 
18. 19. A. Convexa. {Convex Anomia.) Very convex; beak large, prominent; surface smooth. 
20, 21. A. Laevigata. {Smooth Anomia.) Circular, very thin, flat; surface smooth; umbo 
scarcely elevated. 
22. A. Radiata. {Rayed Anomia.) Flat, irregularly orbicular, with fine, radiating striae. 
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