ACEPHALA. 423 
VENUS CALcaREA (Gould). 
Testa ovato-rotundata, alba, crassa, inequilateralis, posticé subtruncata, 
striis concentricis, irregularibus, remotis, lamellosis signata ; natibus 
acutis, attigentibus ; lunula duplicr, ovato-lanceolata ; intus candidts- 
sima ; margine crenulato. 
Venus calcarea, Goutp; Proceed. Boston Soc. Nat. Hist., 1. 277. 
Expedition Shells, 85. 
SHELL ovate-triangular, nearly as high as wide, white, thick and 
heavy, inequilateral, slightly truncated posteriorly; surface marked 
with distant, irregular, somewhat lamellar, concentric ridges, the prin- 
cipal ones being about fifteen in number: beaks smooth, pointed, and 
touching each other; lunule appearing somewhat double, the outer 
one ovate-lanceolate; ligament deeply buried. Interior dead chalky 
white within the pallial impression, polished milk-white outside of it. 
Margin finely crenulate. 
Length two and a half inches; height two inches; breadth an inch 
and two-fifths. 
Inhabits New Zealand. 
This remarkable shell is closely allied to V. exalbida and V. merce- 
naria. It is of a purer white than either, and more elongated, and 
with much fewer concentric rug than the former; nor has it any ra- 
diating striz. 
ARcA SOBRIA (Gould). 
Testa transversa, inequilateralis, rhomboidea, alba, costulis rugosis nu- 
merosis radiantibus, posticis majoribus, instructa, et undulrs remotis 
concentricis subreticulata ; latere antico angusto, rectangulart, in mar- 
ginem ventralem postice desinente ; latere postico oblique truncato, ad 
apicem acuto; apicibus elevatis, angulatis ; area cardinal angusta, 
lanceolata: cardo dentibus ad octo utrinque instructus. 
