TEIBE OSTBACEA. 305 



large, and subfeniform. 3. China, lite ajriccs are not much 

 attenuated. 



O. Laceeans. Hani. 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 inequivalve. 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 7 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. Columbiensis. Hani. 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 lamellae to the margin, 

 which, when permitted by its habitat to expand, branches into wavy 

 foliations : edge of the lower valve (w T hich 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. 



0. Bicolor. Hani. 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. 2^. Senegal? Attached by its 

 entire surface to the bottom of a ship. The lamella, ivhen present, are 

 flattened, 



0. Multisteiata. Hani. Z. P. 1845 ; Conch. Mis. O.f. 3. Sub- 

 orbicular, compressed, of a rich rufous-brown, not solid, the valves of 

 equal size : the lamellae so depressed as to be scarcely manifest, 

 crowded with minute radiating wrinkles, the nacre under the lamellae 

 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. 3^. On a shijj's bottom from Africa. 



0. Callichroa. Hani. Z. P. 1845. Obovate or suborbicular, 

 moderately strong. Valves nearly equal ; upper valve shallow, rayed 

 with purple and yellowish white, covered with depressed concentric 

 lamellae ; lower valve moderately convex, more or less tinged with 



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