ACEPHALA. A41 
riblike, ending in a prominent trigonal knob. A minute cardinal 
tubercle, and a delicate straight lateral lamina bifurcate at tip. Mus- 
cular impressions very indistinct. 
Length two inches; height two and a quarter inches; breadth 
seven-eighths of an inch. 
Inhabits the Feejee Islands. 
A small species coloured much like A. margaritifera ; but the curve 
is in an opposite direction, and it is provided with a well-developed 
auricle, characters which could not be ascribed simply to immaturity. 
Figures 550, 550 a, outer and inner views of the shell. 
AvicuLa FuCcATA (Gould). 
T. saccata, retrorsum obliqua, per-inequivalvis, scabra, rosaceo et flavido 
radiatum picta: auricula pregrandis, elongata; fissura byssali pro- 
Sunda: valva dextra convexiuscula; angulo postico acuto: valva si- 
nistra ventricosa, antice haud emarginata, acutangularis, plica magna 
munita: cardo dentibus conspicuis : margarita argentea, violacescens ; 
limbo cortical cretaceo, croceo et rosaceo radiato. 
Avicula fucata, Goutp; Proceed. Boston Soc. Nat. Hist., iii. 309. 
Nov. 1850. Expedition Shells, 90. 
SHELL obliquely ovate, left valve tumid, right nearly flat; surface 
with short loose lamin, especially behind; colour radiated yellowish 
and rose-red, shining ; dorsal edge produced into a short acute wing, 
externally forming a right angle, then sweeping backwards; anterior 
forming an acute angle and sweeping forwards forms the obliquely 
ovate outline; auricle long triangular, finely and loosely laminated ; 
re-entering angle a right angle, edge sharp and simple. Nacre sil- 
very white, becoming violaceous at edge; calcareous margin pale, 
radiated red; byssal fold sharp and distinct, marking off a broad 
smooth area; cardinal tooth of left valve very strongly developed, in- 
flexed; lateral tooth short, delicate, bifurcate in right valve; muscular 
dots distinct, not impressed. 
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