PLATE LXI.* 
I, 2. Ostrsea Alaeformis. ( Wing-shaped Oyster.) Wing-shaped; umbo near one side; with many divergent ribs 
from umbones ; margins, with many plaits and horizontal frill ;• valves irregular. 
3, 4. 0. Palmetta. ( Palmated Oyster.) Oblong-ovate, depressed; umbo straight, central curved ; with single, 
obscure ear; with many, blunt, oblique ribs; margins plaited. 
5, 6, 7, 8. 0. Lateralis. (Lateral Oyster.) Oblong-ovate, incurved, anterior beak involute; upper valve, with con¬ 
centric lineations ; lo\v r er valve plain, with deep foliations attached by beak. 
9, 10. 0. Triangularis. ( Triangular Oyster.) Triangular, oblong, oblique, with acute beak; surface smoothish. 
II. Plagiostoma Asperum. ( Bough Plagiostoma.) Obovate, sub-compressed, with many, flat ribs, fringed with 
minute, sharp prickles ; lines of growth few. 
12. P. Mantelli. ( MantelVs Plagiostoma.) Obliquely semi-circular; right side truncated ; with radiating striae and a 
few, concentric ones ; lunule hollow, lineated. 
13. 0. Inaequicostata. ( Unequal-ribbed Oyster.) Obliquely quadrangular, umbo much on one side; liinge-line 
nearly parallel ; surface, with many, unequal ribs; margins plicated. 
14. G. Suilla. (Swine Gryphcea.) Sub-orbicular, with concentric, striated laminoe ; upper valve plain; lower with 
short, blunt, oblique beak; lateral edges of lips greatly incurved. 
15. 16. G. DeCUSSata. (Decussated Gryphcea.) Lower valve oblong-oval, convex, with apex laterally attached ; with 
decussated, waved strife. 
17, 18, 19. G. Aquila. (Eagle-leaked Gryphcea.) Obliquely sub-triangular, larger valve deep, with undulated ridge 
from beak to base, whence the side is obliquely wrinkled, with undulating margin; surface from ridge to posterior side 
transversely waved and longitudinally wrinkled; beak large; upper valve flat, with obtuse beak; smooth and uneven in 
centre, other portion with broad, concentric stria). 
20, 21. 0. Lunata. (Crescent-shaped Oyster.) Equivalve, oblong, crescent-shaped, with surface and margins undu¬ 
lating, smooth ; posterior side triangular. 
22, 23. G. Cymbium. (Boat Gryphcea.) Oblong-ovate; upper valve concave, with concentric stria); lower valve 
boat-shaped, with concentric lines and strife; beak acute. Length 51 in., breadth 3|- in. 
24, 25. Pecten Subulatus. (Elongated Pecten.) Elongated, large, sub-ovate, liinge-line straight; ears unequal; sur¬ 
face of upper valve with weak, longitudinal ribs, crossed by minute, undulating, concentric strife; lower valve smooth. 
26, 27, 28. G. Plicata. (Plaited Gryphcea.) Oblong-ovate, arcuated; beaks incurved ; surface rugged, with trans¬ 
verse and longitudinal, irregular, strong, striated ridges and sulci; margins scolloped; inside deep. 
29,32. P. Textilis. (Woven Pecten.) Orbicular; hinge-line oblique; cars nearly equal, obtuse; deeper valve, with 
many, radiating ribs, with wide sulci, crossed by fine, concentric strife ; upper valve flattish, with radiating stria), crossed 
by fine concentric strife; margin slightly crenated. 
30, 31. 0. Sulcifera. (Furrowed Oyster.) Oblong-ovate, inflated; with broad, central sulci from umbones; with 
several, oblique undulations diverging from central sulcus; margins slightly foliated. 
33. Lima Plicatula. (Plicated Lima.) Convex, inequilateral, obliquely ovate, orbicular; anterior side truncated ; 
posterior side produced; beaks projecting; surface, with fourteen or sixteen, divergent ribs; sulci concentrically striated. 
Length in. 
34. Limatula Subauriculata. (Sub-auricled Limatula.) Equilateral, oblong-ovate, convex ; surface, with longi¬ 
tudinal, divergent strife; basal margin finely crenulated. Length ^ in., breadth 4 in. 
35. L. Ovata. (Ovate Limatula.) Equilateral, oblong-ovate, convex; beaks projecting; surface, with from six to 
eight rounded, divergent ribs from beaks. Length -jq in., breadth -£- in. 
( 74 ) 
