224 
PACIFIC SCIENCE, Vol. 1, October, 1947 
U.S.N.M. 32046, 1 specimen from the Indo-Pa- 
cific. 
US.N.M. 543532 (Franco lb), 1 specimen from 
Cebu, P. I. 
U.S.N.M. 543553 (Franco Ig), 1 specimen from 
Cebu, P. I. 
U.S.N.M. 543554 (Franco 3/), 1 specimen from 
Cebu, P. I. 
U.S.N.M. 543555 (Franco 1), 1 specimen from 
Cebu, P. I. 
U.S.N.M. 543556 (Franco 4), 1 specimen from 
Cebu, P. I. 
U.S.N.M. 543557 (Franco 4a), 1 specimen from 
Cebu, P. I. 
U.S.N.M. 543558 (Quadras Coll.), 1 specimen 
from Balagnan Island, Surigao District, Min¬ 
danao, P. I. 
U.S.N.M. 248248, 2 specimens from Tilig (reef), 
Lubang Island. 
U.S.N.M. 1074, 1 specimen from Loochoo Island. 
U.S.N.M. 344827, (Hirase Coll. 2811), 3 speci¬ 
mens from Riukiu Islands, Japan. 
Corculum dionaeum (Broderip and Sowerby) 
(Plate 2, Figure 2) 
1828. Cardium dionaeum Broderip and Sowerby, 
Zool. Jour., vol. 4, p. 367. 
1836 . Cardium unimaculatum Broderip and Sow¬ 
erby, Proc. Zool. Soc. London, pp. 84, 85. 
1845. Cardium dionaeum Reeve, Conch. Icon., 
pi. 21, fig. 122. 
The small size of this species is its most 
characteristic feature. Its range, too, is far 
from that of the other forms here noted. 
The presence of a color mark or marking 
noted for C. unimaculatum, which appears 
to be its only difference from C. dionaeum, 
does not seem to warrant separating the two. 
They appear from the literature to have the 
same distribution. Broderip and Sowerby in 
describing the species state that it was col¬ 
lected by Lieut. Belcher during Beechey’s 
voyage on some island in the south Pacific. 
Reeve cites Anaa as its habitat. Broderip 
and Sowerby also cite Anaa as the place in 
which Cuming collected unimaculatum. 
Shell small, usually white, sometimes with 
red about the escutcheon or various other 
marking. The anterior surface is marked 
with radiatingly curved, rather heavy cords 
which become broader and flatter toward 
the outer margin. They are nodulose, the 
nodules being gradually reduced in strength 
as the cords widen. Microscopic radiating 
lines are present on the cords and in the 
spaces that separate them. The entire sur¬ 
face is also marked by closely spaced, wavy 
incremental lines. The posterior side bears 
the rather long escutcheon below which are 
three nodulose cords and beyond this is a 
series of low, flattened, broad, radiating 
ridges separated by mere impressed lines. 
These ridges are of about the same strength 
as those in the equivalent part of the anterior 
surface. Here, too, the fine radial and incre¬ 
mental sculpture is present. 
The specimen figured, U.S.N.M. 75955, 
was collected by Pease in the Paumotu 
Islands. It measures: height, 21.8 mm.; 
length, 9-5 mm.; diameter, 18.2 mm. 
In addition I have seen the following speci¬ 
mens: 
U.S.N.M. 128480, 5 specimens from Anaa 
Island. 
U.S.N.M. 76814, 4 specimens from Paumotu 
Islands. 
U.S.N.M. 76120, 2 specimens from Paumotu 
Islands. 
U.S.N.M. 42325, 4 specimens from Paumotu 
Islands. 
U.S.N.M. 363437, 1 specimen from Mangaia 
Island, Cook Islands. 
U.S.N.M. 423441, 1 specimen from Lifu. 
U.S.N.M. 32046a, 2 specimens from the Indo- 
Pacific. 
U.S.N.M. 17468, 1 specimen from the Pacific 
islands. 
Corculum obesum, new species 
(Plate 1, Figure 2) 
The distinctive characters of this species 
are the extreme obesity of the anterior sur¬ 
face combined with the concave ventral side, 
the margin being denticulated as in C. 
cardissa. 
This species appears to be less in size than 
C. cardissa. The anterior surface is very 
greatly elevated, whereas the posterior is only 
slightly elevated near the escutcheon and 
concave from there to the outer margin. The 
anterior surface is marked by radiating nodu- 
