APPENDIX. 355 
edges rather convex and somewhat sloping; anterior side bluntly 
subangulated, bluish ash-coloured above ; posterior extremity rounded ; 
beaks not inclined, often eroded; lunule obsolete; inside whitish, 
stained with purplish liver-colour in front, anterior tooth slightly 
crenulated, scarcely any pallial sinus. 9...14. Malabar. 
CYTHEREA OBLIQUATA (t. 15, f. 24), Hanl. Z. P. 1844, p. 109.— 
Sow. Th. 2, t. 1383, f. 125.—Dione o. Desh. Vener. p. 65. Ovate- 
cordate (sometimes oblong-cordate), more or less tumid, rather strong, 
nearly smooth, whitish, speckled with minute brown scattered linear 
zigzags, which become denser upon the swollen umbones ; ligamental 
edge rather convex, somewhat sloping; ventral edge subarcuated, 
entire; lunule large, indistinct, colourless; beaks white, very slanting ; 
ligament narrow; hinder extremity obtuse; inside white or pink. 
13...24. Philippines. 
CYTHEREA RIVULARIS (t. 15, f. 25, as C. scrrpra, VAR. !)—VENUS R. 
Born, t. 5, f. 7, teste Desh.—Crrcr r. Sow. Th. 2, p. 652, t. 139, 
f. 46, 7, 8.—Desh. Vener. p. 84. Subquadrate, flat, solid, very im- 
equilateral, glossy, white or yellowish white, with usually 2 or 3 im- 
perfect chestnut rays, encircled with very narrow distant convex 
folds that often (? usually) become obsolete in front and near the 
arcuated and entire ventral margin, and are decussated by short 
narrow curved diverging folds near the dorsal edges, of which the 
front one is convex and moderately sloping, and the hinder one 
straightish and much sloping; umbones flattened; beaks acute; 
slopes flat, chestnut-stained; ligament sunken; inside tinged with 
rose-colour. 2. Australia. 
CyTHEREA CyriL1i (t. 15, f 26).—Vunus C. Scacchi, Lettera Test. 
Napolit.—C. aptcauts, Phil. 1, p. 40, t. 4, f.5. Small, rounded- 
triangular, rather compressed; glossy, speckled with pale chocolate 
linear markings on a whitish ground, and usually adorned with a few 
broken rays of the same hue; closely and finely grooved throughout ; 
ventral edge entire, subarcuated ; ligamental edge convex, not much 
sloping; hinder dorsal edge straightish or subretuse, much sloping ; 
beaks acute, prominent, inclined; lunule rather large, oblong-cor- 
date, Imconspicuous; ligament sunken; teeth and scars of section 
Circe. 4. Mediterranean. Evidently a variety of C. Minima. 
CYTHEREA AFFINIS (t. 15, f. 27), Brod. Z. P. 1835, p. 45.—Sow. 
Th. 2, p. 680, t. 1382, f. 101. — Dione a. Desh. Vener, p. 73. 
I regard this shell as only a flattened variety of TORTUOSA, with 
the concentric ridges sharper and more distant. 1...14. W. 
Columbia. 
CYTHEREA ALBIDA (t. 15, f. 31).—List. t. 273, f. 109, quoted as 
Vunus A. by Gm. 3287.)—CuHiongE A. Gray, Analyst.—C. Kinait, 
van. Sow. Th. 2, t. 133, f. 181, probably—Dtone a. Desh. Vener. 
