TRIBE OSTRACEA. 305 
large, and subreniform. 3. China. The apices are not much 
attenuated. 
O. Lacerans. Hanl. Z. P. 1845. Longitudinal, elongated, narrow 
at the acute beaks, and forming more or less numerous claw-like pro- 
jections at the base and sides, not at all lamellated, moderately strong, 
very iequivalve. Upper valve nearly smooth, flat, either yellowish 
with dull crimson irregular rays, or of the latter colour with two central 
radiating streaks enclosing usually a narrow space of yellowish white : 
lower valve profound, whitish, or pale orange, with a few broad 
radiating streaks of blackish purple, and armed with a few distant 
subangular longitudinal. ribs. Inside of an uniform silvery white; no 
cardinal denticulations ; cartilage conical. 2. Senegal? Not unlike 
Parasitica, but distinguishable by its claw-like projections; never 
attached by the entire surface. 
O. CotumBiensis. Hanl. Z. P. 1845. Ranging in shape from 
suborbicular to oblong, not solid, rayed with purple on a white ground. 
Valves of equal length, but the shelly substance of the upper one fits 
into the lower, and is only continued by the lamelle to the margin, 
which, when permitted by its habitat to expand, branches into wavy 
foliations: edge of the lower valve (which is not so shallow, and is 
usually attached by its entire surface) elevated. Inside whitish, 
somewhat nacreous; no cardinal denticles: scar reniform, moderate. 
2. W. Columbia. 
O. Brcotor. Hanl. Z. P. 1845; Conch. Mis. Os. f. 2. Obovate, 
never elongated, rather thin or moderately strong, somewhat com- 
pressed, inclined to expand laterally, scarcely lamellated, brownish 
purple with one or two broad white rays: margin simple, sometimes 
undulated by the substances to which it adheres: beaks rather 
pointed: inside white, edged in the upper valve by the external 
colouring; no cardinal denticles. 24. Senegal? Attached by its 
entire surface to the bottom of a ships: The lamella, when present, are 
flattened. 
O. Mutrisrriata. Hanl. Z. P. 1845; Conch. Mis. O. f. 8.  Sub- 
orbicular, compressed, of a rich rufous-brown, not solid, the valves of 
equal size: the lamella so depressed as to be scarcely manifest, 
crowded with minute radiating wrinkles, the nacre under the lamellie 
stained with rufous. Inside snowy white, edged with purple in the 
upper valve, and stained in the lower with brilliant dark red in the 
central disc: scar rather large: beaks not prominent: cardinal 
denticles strong. 33. Ona ship’s bottom from Africa. 
O. Catticuroa. Hanl. Z. P. 1845.  Obovate or suborbicular, 
moderately strong. Valves nearly equal; upper valve shallow, rayed 
with purple and yellowish white, covered with depressed concentric 
lamelle ; lower valye moderately convex, more or less tinged with 
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