364 TESTACKOUS MOLLUSGA. 
C. Mortoni, p. 140, t. 16, f. 50, 51 ... C. fragile, p. 141, t. 17, f. 51 
wtiC. dynatum,p. 141, t217, 20.1)... 0. tumonterum, p. 14 a.ais, 
f. 50 ... C. monstrosum, p. 148, t. 17, f. 32 ... C. lineatum, p. 148, 
t. 16, f. 53 ... C. umbricatum, p. 143, t. 17, f. 42 ... C. fornicatum, 
p- 148, t.17, f. 49 ... C. biangulatum, p. 148, t.17, £19 ... C. plani- 
costatum, p. 144, t. 17, f. 48 ... C. subretusum, p. 144, t. 17, f. 29. 
CaRDIum Lacunosum (t. 16, f. 52), Reeve, Z. P. 1845; I. Car. 
f. 81.  Ovate or elongated-ovate, usually somewhat oblique, subequi- 
lateral, thick, tumid, ochraceous-yellow, usually paler m the umbonal 
region, spotted and sometimes banded with livid red, radiated with 
from 80 to 34 narrow prominent ribs, whose sides are more or less 
concave, and whose wrinkled intervals in front are broader above than 
below. Central ribs crenated or serrato-crenated on each side, extreme 
front ribs with oblique compressed scaly tubercles ; hinder ribs closely 
set with flattened scaly plates, the rounded tops of which imbricate 
each other upwards (in the direction of the umbones). Ventral edge 
peculiarly arcuated, stained inside with crimson in front; lunular site 
brownish lake; beaks scarcely inclined; inside white, with 2 shortish 
umbonal rosy rays. 2. Zanzibar. The flattened summit of the ribs 
forms a protruding ledge. 
CaRDIUM RUBICUNDUM (t. 16, f. 54), Reeve, Z. P. 1844, p. 169; 
I. Car. f 144. Like C.lacunosum, yet scarcely so tumid, the ground- 
colour rosy, speckled with orange-brown, and variegated with white, 
with 37 ribs, whose intervals are narrower, the scales on the anterior 
ribs sharper, and not restricted ventrally to the extreme costa. 2. 
Zanzibar. The internal rays less distinct and often ochraceous. 
CARDIUM OBOVALE (t. 17, f. 10), Sow. Z. P. 1833, p. 84.—Sow. 
C. I. Car. f. 4.—fReeve, I. Car. f. 117. Peculiarly oblique, peaked 
oval, longer than broad, rounded at both ends, solid, tumid, wholly 
white, with about 21 radiating ribs, of which the 7 front ones are 
smooth depressed and divided by narrow intervals, the next 3 larger 
prominent and regularly crenated by closely-disposed subarcuated 
concentric raised lines, the remainder less elevated, broader than their 
intervals, and smooth, except their front edges, which are serrato- 
crenated; the costal interstices very finely and closely cancellated 
concentrically ; no umbonal ridge; umbones almost terminal; no de- 
fined lunule. 3...4. W. Columbia. 
Carpium Dionamvum (t. 17, f. 11), Sow. Z. J. 4, p. 367; Beech. Z. 
t. 42, f. 6—Sow. C. I. Car. f. 52.—Reeve, I. Car. f. 122. Small, 
subrhombie, very inequilateral, white, radiatingly ribbed, with a 
remotely spinous carinated angle running very obliquely from the 
beaks to the peaked and projecting anterior extremity. Valves tumid 
at the keel, laterally compressed, broadly biangulated in front, rounded 
behind. Ribs depressed, especially the front ones (except the two 
