130 
Umbones acute, incurved, approximate ; the lunule is broadly 
lanceolate and shallow, each valve equally contributing to its 
formation ; escutcheon very narrow and slightly depressed, with 
subangular margins. 
Right valve with a cardinal tooth and an anterior lateral 
tooth; the posterior lateral is imperfectly developed. Left valve 
with two divergent cardinal teeth ; there are no laterals. Inner 
margin of valves plain. 
Dimensions.—Antero-posterior diameter, 11; anterior radius, 
6:5; posterior radius, 4°5 ; umbo-ventral diameter, 10; sectional 
diameter, 6 mills. 
Habitat.—Three miles off Rickaby, Hardwicke Bay, Spencer 
Gulf, in eight fathoms. One perfect shell (Dr. Verco). 
This new species has much the outline of L. quadrata, Angas, 
though with a less arched antero-dorsal margin. The concentric 
ornamentation, the great inequilateral form and the simple 
dentition are associated characters, which give distinctness to 
this species. 
Cardita gemmulifera, spec. nov. Pl. i., fig. 9. 
A single living specimen of a Cardita taken in company with 
C. Beddomei, in 174 fathoms off Corney Point by Dr. Verco, 
differs sufficiently from that species to justify a distinctive 
denomination. The cost are ornamented with close-set rounded 
tubercles in place of narrow tranverse ones, and the sectional 
outline of the shell is slightly more tumid. 
Dimensions.—Antero-posterio, 10 ; umbo-ventral, 9 ; sectional 
diameter, 6°75 mm. 
Lithodomus projectans, spec. nov. Pl. i., fig. 1. 
Shell cylindrical-oblong ; umbones tumid, involute, projecting 
beyond the anterior margin; somewhat narrowed posteriorly, 
without angulation, to the roundly-truncated margin ; anterior 
margin rounded ; post-dorsal margin strongly arched; ventral 
margin nearly straight, but slightly curved antemedially. 
Test covered with a reddish-brown, thick, glossy epidermis, 
marked with a few linear sulci which pass into abrupt subim- 
bricating folds on the posterior slope. Interior of a violet-brown 
colour. 
Dimensions.—Antero-posterior diameter, 28; greatest trans- 
verse diameter, 12:5; sectional diameter, 12 (vix.). 
Locality.—Port Darwin (W. 7. Bednall). 
This species is conspicuous by its projecting umbos and strongly 
arched dorsal line, in which particulars it resembles Z. cinna- 
moneus, Chemnitz, from which it differs by its less arched dorsal 
line, straighter ventral margin and by the adsence of decussated 
sculpture. It is referred to under Z. brevis, Tate, Trans. Roy. 
