PLATE LXXXIY. 
1. Venus Turgida. (Swollen Venus.) Orbicular, gibbose ; hinge strong; beaks large, rounded; surface, with many, 
concentric ridges ; with a series of crenulations inside; margin thickened ; shell thick. 
2, 3. V. Submersa. (Bulged Venus.) Orbicular, tumid ; beaks approximate; lunette obscure; posterior side trun¬ 
cated ; surface smooth. 
4. Cytherea Incrassata. (Thickened Cytherea.) Orbicular, oblique, sub-compressed, smooth ; with shallow lines of 
growth; lunette lai'ge, ill-defined ; internal margin entire. 
5. V. RugOSa. (Rough Venus.) Sub-triangularly sub-cordiform; convex ; lunette oblong, cordiform; beaks turned 
to one^side; surface, with rough, concentric ridges; margin blunt, crenated internally. 
6. V. Gibbosa. (Inflated Venus.) Orbicular, gibbous; hinge-area strong, broad; anterior side truncated; lunette 
large, short; surface, with distant, concentric lines of growth; inner edge with fine crenulations. 
7. C. Rotundata. (Bounded Cytherea.) Orbicular, gibbose ; surface, with many, deep, concentric strive. 
8. V. Sublcevis. ( Half-smooth Venus.) Elliptical, compressed; beaks pointed; lunette ill-defined; surface smooth, 
with a few, shallow lines of growth. 
9. V. Immersa. (Immersed Venus.) Transversely elliptical, compressed; beaks acute ; lunette sunk ; back and base 
curved; posterior side narrowed; surface smooth, with remote lines of growth. 
10. V. Gallina. (Ren Venus.) Sub-triangularly sub-cordiform ; convex; beaks approximate; lunette oblong, with 
longitudinal stria 3 ; surface, with many, rounded, concentric ribs; internal margin finely crenated. 
11. 12. C. RugOSa. (Rough Cytherea.) Sub-triangular, acuminated towards beaks; posterior extremity pointed; 
valves convex near beaks ; surface, with many, concentric sulci. 
13. C. Dolobra. (Axe-shaped Cytherea.) Sub-triangular; convex; beaks produced; lunette narrow; posterior side 
straightish; surface smooth, with a few, remote lines of growth. 
14, 15. V. Tenera. (Tender Venus.) Lenticular, transverse; beaks acute; surface, with fine, concentric strim; 
lunette lanceolate. , ,, 
16. V. Ovalis. (Oval Venus.) Transversely oval, convex; beaks well-defined; lnnette obsenre, prominent, smooth; 
surface, with many, concentric strise. 
17. V. Varicosa. (Warted Veniu.) Sab-globose; beaks large, produced, incurved; surface, with shallow, concentric 
sulci and two, longitudinal, varicose ridges within each valve. 
18. C. Chione. ( Chione’s Cytherea.) Obliquely ovate, convex; beaks small, incurved; lunette cordiform; surface 
smooth, shining, with a few, concentric lines of growth; margins thick, rounded; pallial impression within broad, trans¬ 
verse sinus. . . , 
19. C. Convexa. (Convex Cytherea.) Sub-triangular; beaks central; sides abruptly sloping; base straight; surface, 
with shallow, concentric sulci. 
20. C. Parva. (Small Cytherea.) Transversely obovate, convex; beaks obtuse; surface smooth, with remote, shallow 
lines of growth ; lunette narrow. 
21 . C. Elegans. (Elegant Cytherea.) Obovate, convex; beaks obtuse; lunette oval; surface glossy, wit i concentric 
22, 23. C. Tenuistriata. (Thin-striated Cytherea.) Sub-triangular, gibbose, smooth; anterior side concave; beaks 
prominent; lnnette broadish, pointed ; surface, with many, concentric strife. 
24, 25. V. Faba. (Bean Venus.) Transversely obovate; sub-compressed; beaks short; lunette deep, lanceolate; 
surface, with many, concentric strife and lines of growth. 
26. C. Truncata. (Truncated Cytherea.) Sub-quadrate; posterior side large, truncated; back arcuated; base straight; 
lunette lanceolate, obscure; surface, with strong lines of growth. 
27. C. Plana. (Plain Cytherea.) Elongated, sub-depressed; anterior side concave under beaks, rounded below; 
posterior side arcuated ; surface smooth ; lunette lanceolate. 
28. C. Lilieolata. (Lineated Cytherea.) Transversely ovate, sub-cordate, ventricose; anterior side smooth ; the rest 
with zig-zag strife; beaks prominent; internal margin entire ; shell very thick. 
29 ° C. Subrotunda. (Half-round Cytherea.) Lenticular, orbicular, compressed; lunette narrow, lanceolate; beaks 
obtuse; surface smooth. 
30. C. Caperata. (Wrinkled Cytherea.) Orbicular, compressed, lenticular; lunette cordiform; surface, with many, 
rounded, concentric ridges and widish intervening sulci. 
( 103 ) 
