488 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
toward the anterior base; on the fourteenth rib there are two rows of scales, and on the ribs behind 
this they point toward the posterior base; the rest of the surface of the ribs and the grooves between 
them are nearly smooth; within the central ribs are distinctly shown; serrations around the edges of 
the shell strong. Color whitish, buff, tawny, or brownish, sometimes variegated; within, whitish or 
yellowish, sometimes streaked or marked with brownish purple. 
Length, 35; height, 40; diameter, 28 mm. 
San Antonio Bridge; San Juan; Mayaguez, Porto Pico. 
Cardium leucostoma Born. 
Cardium leucoslomum Born, Test. Mus. Caes. Vind., p. 46, pi. in, fig. 6, 1780. 
San Juan Harbor, Porto Rico, one young shell. 
This species was regarded by Wood, with much probability, as being the original C. magnum of 
Linnaeus (not of Born), but there is no way of proving this and so the name is best left as it is. The 
species in a general way resembles C. isocardia, but wants the spinose sculpture, has the sides of the 
ribs crenulate, and is more compressed. It is found in collections labeled C. marmoreum Lamarck and 
C. elongatum Wood, or C. subelongatum Sowerby, all later names than that of Born. 
Cardium isocardia (Linnaeus) Reeve. 
Cardium isocardia Linnaeus (ex parte) , Syst. Nat., ed. x, p. 679, 1758; Reeve, Conch. Icon., n.Mon. Cardium, pi. xvii, fig. 84, 1845. 
Off Boca Prieta, Porto Rico, in 8 fathoms, sand, at station 6075, living. 
The form common in Florida has 27 to 30 ribs, and the spinose decoration is less dense than that 
in the typical West Indian form, which has 30 to 35 ribs. In the former the periostracum is more 
dense and dull colored, and the channels between the ribs, owing to the less-developed sculpture, 
appear wider. This variety was named C. egmontianum by Shuttleworth, and the name seems worthy 
of retention in a varietal sense. The typical C. isocardia is brighter colored and has more yellow 
inside than the variety. C. eburniferum Guppy appears identical with the typical C. isocardia. 
Subgenus Fkagum Bolten, 1798. 
Section TRIGONIOCARDIA Dali, 1900. 
Cardium antillarum d’Orbigny. 
Cardium antillarum d’Orbigny, Moll. Cubana, II, p. 309, pi. xxvii, figs. 53-55, 1845. 
Cardium ceramidum Dali, Bull. Mus. Comp. Zool., Cambridge, xii, 1886, p. 269, pi. rv, fig. 6. 
Shell small, quite inequilateral, solid, moderately inflated, with from eighteen to twenty ribs, the 
last six or seven on the posterior area crossed by fine, irregular, sharp, concentric threads. Of these 
the last four or five are nodulous; the next two are without nodules; the central ribs are very strong, 
gradually becoming smaller toward the anterior end; they all have a row of nodules or heavy scales 
and the spaces between them are concentrically grooved; sometimes the ribs, if worn, are nearly 
destitute of scales, and in other cases they are all more or less scaly: within, the ribs show faintly; beak 
cavities deep; hinge and teeth strong. Color white or yellowish throughout. 
Length, 10; height, 9.5; diameter, 7 mm. 
Mayaguez Harbor, Porto Rico, many dead valves at stations 6058, 6061, 6062; San Juan Harbor, 
one valve. 
Section FRAGUM s. s. 
Cardium medium Linnaeus. 
Cardium medium Linnaeus, Syst. Nat., ed. x, p. 678, 1758: Reeve, Conch. Icon., ii, pi. vi, fig. 30, 1844. 
Shell inequilateral, subrhomboid, solid, with a high, rounded posterior ridge, behind which it is 
subtruncate, with thirty-five or thirty-six moderately strong, nearly smooth ribs; about ten of these, 
which are on the posterior slope, are rounded and have rather deep grooves between; those of the 
rest of the shell overhang the deep, rounded grooves between them; teeth strong. Color whitish or 
buff, variously painted with brown or brownish purple. 
Length, 85; height, 37; diameter, 30 mm. 
Mayaguez Harbor, Porto Rico, at station 6062; Vieques. 
