357 
Cuna concentrica, Hedley. 
Cana concentrica, Hedley, Mem. Austr. Mus., vol iv., 1902, p. 
315: Verco, Trans. Roy. Soc., S. Austr., vol. xxxi., p. 109, q.v. 
Cuna edentata, n. sp. PI. xiy., f. 1 to 3. 
Shell ovate-trigonal, white, glossy, solid. Anterior and 
posterior lateral borders nearly straight, the latter rather 
shorter. Ventral border convex, slightly produced anteriorly. 
A small prominent prodissoconch cap, about three-fourths of 
a circle. Exterior has crowded concentric valid ribs, but no 
radial sculpture. The right valve has a large central tri- 
angular tooth, a minute anterior, at the extremity of the 
long antero-lateral tooth, which is separated by a groove 
from the margin, a marginal postero-lateral, with a minute 
cardinal tooth above it, and above that a marginal socket 
for the left posterior cardinal. The left valve has a large 
anterior cardinal tooth, and a small posterior behind the 
cartilage-pit, a long low postero-lateral tooth separated by a 
groove from the margin, and a marginal antero-lateral. 
The inner ventral border is not dentated, whence the 
name. 
Dim.—Antero-posterior diameter, 16 mm.; umbo-ven- 
tral, 1°9 mm. 
Hab.—Gulf St. Vincent, dredged several. 
Diagnosis.—It is very like C. concentrica, Hedley, but 
the smooth internal ventral border distinguishes it. 
Type in Dr. Verco’s collection. 
Cuna comma, n. sp. Pl. xvii., f. 29 to 31. 
Shell solid, white, glossy, obliquely pyriform, with a 
distinct three-quarter circle prodissoconch. Antero-lateral 
border convex; postero-lateral concave below the umbo, then 
straight, much shorter; ventral border convex produced an- 
teriorly. Outer surface closely concentrically ribbed, no 
radial sculpture. The right valve has a large central curved 
cuneate tooth in front of the cartilage-pit, and a small pos- 
terior tooth just below the umbo, with a little socket out- 
side and below it. The left valve has a large curved anterior 
tooth, a lamina in front of the cartilage-pit, a small pos- 
terior tooth behind the pit, and a small socket above and in 
front of it. The antero-lateral in the right valve and the 
postero-lateral in the left are separated from the margin by 
a groove to receive the corresponding marginal lamina of the 
other valve. The internal ventral border is not denticulated. 
Dim.—Antero-posterior diameter, 2°6 mm.; umbo-ven- 
tral, 3°2 mm. 
Hab.—Dredged alive in 22 fathoms in Backstairs Pas- 
sage, and in 20 fathoms off Newland Head; also in Gulf St. 
