Corculum of Pacific and Indian Oceans— Bartsch 
U.S.N.M. 545544 (Franco 1/). The specimen 
figured measures: height, 36.7 mm.; length, 20 
mm.; diameter, 35.3 mm. Dr. Franco states that 
she has one measuring: height, 49 mm.; length, 
47 mm.; diameter, 28 mm. 
In addition to the figured specimen, the U. S. 
National Museum has: 
U.S.N.M. 7675, 2 specimens from the U. S. 
Exploring Expedition, with no locality. 
U.S.N.M. 545545 (Franco 2a), 1 specimen. 
U.S.N.M. 545546 (Franco le), 1 specimen. 
U.S.N.M. 545547 (Franco Id), 1 specimen. 
U.S.N.M. 544829a (Hirase 2813), 2 specimens 
from Osima, Osumi, Japan. 
Corculum cardissa (Linnaeus) 
(Plate 1, Figure 3) 
1705. Cartissae, Hertjes, etc. Rumphius Am- 
boinsche Rareteitkamer, pi. 42, fig. E, p. 132, 
in part. 
1758. Cardium cardissa L., Syst. Nat., p. 678, no. 
59. 
Linnaeus adopted Rumphius’ name, 
placing it in his genus Cardium as Cardium 
cardissa. He cites Rumphius’ plate 42, figure 
E. Rumphius states that the most and best 
are found on Nussalaut (now called Noesa- 
laoet Island) and a few on Hitoe Island. 
Rumphius, in addition to the one figured, 
recognized two other forms which he de¬ 
scribed in his text and which have subse¬ 
quently received names, as will be stated in 
the following pages. 
The striking features of this species are its 
large size and the strong, slender, almost 
spinose denticles of the outer edge of the 
valves. The two sides are about equally con¬ 
vex on the early shell. In adult shells the 
outer edge curves anteriorly, leaving the 
valves between the outer edge and the middle 
concave, or dished. The anterior surface is 
marked by rather broad^ depressed radiating 
cords which are about as wide as the spaces 
that separate them. These cords bear nodules 
which are quite regularly distributed in ver¬ 
tical as well as horizontal series. They are 
best developed in the early part of the shell. 
In the spaces separating the radiating cords 
fine threads are present, which are crossed 
by closely spaced transverse threads. The 
223 
posterior valve bears the horn-colored, heart- 
shaped escutcheon near the umbones which 
is followed usually by four or more broadly 
triangular ridges bearing regularly distrib¬ 
uted cusps on their crests. Between these 
cords and the denticulated outer edge, 
weakly developed and more closely spaced 
cords are present. The spaces between the 
cords show fine threads paralleling the cords, 
while regularly, closely spaced, stronger 
threads cross them. 
The coloration of the anterior surface may 
be soiled white, or yellowish white, or yellow 
unicolor, or slightly rayed. 
One specimen, U.S.N.M. 545548 (Franco’s 3e), 
has a dark brown umbonal pit. The posterior 
side usually shows a watered-silk effect, the pat¬ 
tern being arranged in both radiating and con¬ 
centric series. 
One specimen, U.S.N.M. 545549 (Franco’s 3 a), 
has a series of bright red spots arranged in radi¬ 
ating series. 
U.S.N.M. 545550 (Franco’s 3) has the outer 
edge of the basal part rose-red on both sides. 
The specimen figured, U.S.N.M. 545551 
(Franco’s la), measures: height, 56.2 mm.; 
length, 27.8 mm.; diameter, 52.7 mm. Our largest 
specimen, U.S.N.M. 7675, one of a series of 
14 obtained by the U. S. Exploring Expedition 
bearing the label "Pacific Islands,” measures: 
height, 66.5 mm.; length, 31.2 mm.; diameter, 
63.2 mm. 
U.SN.M. 151464, 1 specimen from India. 2 
U.S.N.M. 521687, 5 specimens from Nicobar 
Islands. 2 
U.S.N.M. 7675, 14 specimens from the Pacific 
Islands (Exploring Expedition). 
U.S.N.M. 75908, 1 specimen from the Indo- 
Pacific. 
U.S.N.M. 2544, 2 specimens (no locality). 
U.S.N.M. 75596, 2 specimens from the Indo- 
Pacific. 
U.S.N.M. 120185, 1 specimen from the Indo- 
Pacific. 
U.S.N.M. 17465, 1 specimen from the East 
Indies. 
2 The Indian Ocean specimen measures: height, 
42 mm.; length, 17.2 mm.; diameter, 38.8 mm. 
The largest Nicobar specimen measures: height, 
38 mm.; length, 15.7 mm.; diameter, 34.1 mm. 
It is quite possible that the specimens from the 
Indian Ocean may represent a smaller race that 
may require a name in the future. 
