353 
It may reach 10 mm. in length and 10 mm. in height. 
When young the shell is comparatively longer antero- 
posteriorly than when adult, the umbos seem to project more 
dorsally, and the sectional diameter is less, so that the juven- 
ile form might be mistaken for another species. To the char- 
acters given by Tate may be added that the shell may be 
white with dark-brown muscle scars and hinge-plate and 
pallial line, and in addition some have all the inner ventral 
part from above the pallial line to the margin a deep purple- 
brown. Rarely the whole shell has a light purple tint. 
Carditella elegantula, Tate and May. 
Carditella elegantula, Tate and May, Proc. Linn. Soc., New 
South Wales, vol. xxvi., 1901, part 8, p. 484. Type locality.— 
Blackman’s Bay, Tasmania. 
Dredged alive in Backstairs Passage in 22 fathoms and in 
18 fathoms; also in Investigator Strait, 22 fathoms; dead in 
Spencer Gulf; Port Willunga (Mr. Kimber). 
Carditella valida, n. sp. Pl. xvi., f. 22 to 24. 
Shell solid, obliquely transversely oval, somewhat pro- 
duced anteriorly. Umbos prominent, curved forward, 
acute, approximate, with a minute prodissoconch cap. Post- 
dorsal border markedly convex; anterior concave; ventral 
convex, more curved in front than behind, crenulate, About 
nineteen valid axial ribs, rounded, interspaces very narrow. 
Valid close-set concentric round cords cross the coste, scarcely 
visible in the interspaces. The right valve has a wide tri- 
angular cardinal tooth, an anterior lateral separated by a 
groove from the margin, and a posterior marginal lateral. 
The left valve has two diverging cardinals, of which the pos- 
terior is the larger, a posterior lateral separated by a groove 
from the margin and an anterior marginal lateral. The in- 
ternal ventral border is well denticulated. Lunule cordiform, 
depressed, smooth. Escutcheon long, lanceolate. Ligament 
visible externally. Colour brownish, especially over the pos- 
terior third. Internally brown in the posterior part fading 
anteriorly, lateral teeth brown, and inside the ventral mar- 
gin. It may be wholly white, or of a very light purple tint. 
Dim.—Antero-posterior diameter, 3°7 mm.; umbo-ven- 
tral, 3°6 mm. 
Hab.—Encounter Bay (Tate); Gulf St. Vincent, under 
22 fathoms, several alive and many valves. Taken in small 
numbers and poor condition in 25, 40, 62,410, and 130 
fathoms, from Beachport west to the Neptune Islands. 
Diagnosis.—It was recorded by Tate for South Australia 
as C. infans, BE. A. Smith, in Trans. Roy. Soc., 8. Austr., 
L 
