ACEPHALA. A13 
concentricé striolata ; apicibus medianis, elevatis, acutis, contiguis, an- 
trorsum versis ; latere antico superne subangulato, excavato ; latere 
postico rotundato, infra paululum producto: cavositas albida ; cicatra- 
cibus conspicuis: cardo invalidus ; dentibus apicalibus duobus divari- 
catis, lateralibus nullis. 
Lucina inculta, Goutp; Proceed. Boston Soc. Nat. Hist., i. 255. 
June 1850. Expedition Shells, 82. 
SHELL small, thin, lenticular, equilateral, nearly circular; dull 
white colour; surface rude, with no sculpture save the slight concen- 
tric undulations produced by irregular stages of growth. Beaks 
slightly elevated, rather compressed, acutely triangular, incurved, a 
slight depression in front of them rendering the anterior half a little 
less elevated than the posterior; anterior end somewhat acutely 
rounded; posterior and basal margins circularly rounded, most depend- 
ing portion a little behind the middle: valves moderately convex, 
greatest breadth a little behind the centre. Interior dead, dirty white; 
margin simple; hinge delicate; cardinal teeth two in each valve, 
divergent, one of which is bifid, none lateral. Ligament external. 
having a golden metallic lustre. 
Diameter three-fourths of an inch; breadth three-eighths of an inch. 
Inhabits New Zealand. 
Very much like L. flan, but is much smaller, more solid, and less 
glossy. The anterior end is less developed, and the bulk of the shell, 
as well as its most depending portion, is behind, instead of before the 
beaks. 
Figure 524, side of the shell; 524 a, inside and hinge; 524 0, back 
of the shell. 
LuciNA LENTICULA (Gould). 
Testa parva, solidula, lenticularis, rotundata, convexiuscula, concentrice 
imbricato-striata, etiam striis radiantibus decussata, alba, epidermide 
fuliginoso hic illic induta; apicibus fere mediantis, prominulis: cardo 
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