TRIBE PECTINIDES. ~ 295 
as almost to become obsolete in the more typical examples: interstices 
sculptured. 23. China. 
S. Gussonr. Costa, Tes. Sic. p. 42.—Phil. 1, p. 87, t. 5, f. 16; 
2, p. 63.— Kust. vil. 2, t. 6, f. 3, 4.—Sow. Th. 1, p. 430, t. 89, f. 54. 
—S. Axpipus, Brod. Z. P. 1836, p.43.—S8. Minimus, Chenu, Il. C. 
Sp. t. 24, f. 3. Small, wholly white both within and without, sub- 
ovate, more or less compressed at the sides dorsally, scarcely eared, 
merely radiated in both valves by very numerous narrow unarmed 
costelle or coarse raised strize: inner margin closely and strongly 
crenated. 4. Mediterranean. The attached valve is usually gibbous. 
S. Asperrimus. Sow. Z. P. 1847; Th. 1, p. 421, t. 87, f. 38. 
Colour (in the few specimens known) pinkish drab; entire surface 
most closely rayed with crowded costelle and elevated strive, that 
everywhere bristle with more or less elevated small spines. None of 
the costellz are peculiarly prominent, but each, as it is permitted to 
develop itself, becomes squamiferous and finally aculeated. 4. U. 
S. Lineva-Fetis. Sow. Z. P. 1847; Th. 1, p. 420, t. 88, f. 50. 
Solid, of an uniform dull orange-red, crowded with most numerous 
(about 70) equal-sized radiating costelle, which are armed with most 
thickly set short squamular spines; interstices narrow and smooth. 
An Uo 
TRIBE OSTRACEA. 
Ligament either internal or nearly so: shell irregular in form, 
foliaceous, or at times papyraceous. 
OSTREA.? 
Shell affixed, inequivalve, wregular; the beaks not touching, but 
rather diverging, the lower one often produced ; upper valve the smaller, 
and in growth enlarging anteriorward ; devoid of regular teeth, but 
usually provided with denticles on either side of the hinge; ligament 
semi-internal, its pit increasing with age. 
* Margin not in folds, but simple or waved. 
O. Evuuis. Lin. 1148.—Lam. 1.—D. p. 280.—Turt. B. p. 204. 
—Mont. p. 152.—Sow. G.—Reeve, t. 120, f. 1.—List. t. 193, f. 30. 


1 See, too, the S. ConrrARius and SpryuLosus of Kuster (Ch. ix. 
f. 985, 6, and 988, 9, 90), the S. Lamarck, Dicirarus, FRaGiis 
and Untcotor of Sowerby’s Monograph (Thes. Conch.), and the 
S. Ampicuus, Excavatus, Rosrratus, Gracizis, Lima and Asiaticus 
of Chenu’s ‘Illustrations.’ The two last (Il. C. Sp. t. 24, f. 7, and 
t. 24, f. 1, 4) are new to me. 
We have followed Deshayes in excluding the genus GrypHaa, 
