MOLLUSCA OF PORTO RIOO. 
489 
Subgenus Papyridea Swainson. 
Cardium spinosum Meuschen. 
Cardia spinosum Meuschen, Mus. Gevers. , p. 442, 1787. 
Solen bullatum Chemnitz, Conch. Cab., vi, p. 65, figs. 49, 50, 1782; not of Linnteus. 
Cardium bullatum Reeve, Conch. Icon., n, pi. II, fig. 8, 1844. 
San Juan, Porto Rico (Gundlach). 
Cardium semisulcatum Gray. 
Cardium semisulcatum Gray, Ann. Phil., IX, p. 137, 1825. 
Cardium petitianum d’Orbigny, Moll. Cubana, II, p. 309, pi. xxvii, figs. 50-52, 1845. 
Shell small, elliptical, thin, very inequilateral, moderately inflated, with numerous low ribs, 
and with more or less perfectly developed smaller ribs between the larger ones, the margin at the 
posterior end sharply toothed; surface covered with fine concentric growth lines, which are stronger 
on the anterior part of the shell; interior showing the sculpture; hinge teeth compressed. Color 
whitish or yellowish, with faint brown blotches and spots. 
Length, 10; height, 6.5; diameter, 5 mm. 
San Juan, Porto Rico, one valve; off Boca Prieta, Porto Rico, one specimen on Spondylus. 
Subgenus Ltevicardium Swainson, 1840. 
Cardium serratum Linnaeus. 
Cardium serratum Linnseus, Syst. Nat., ed. x, p. 680, 1758. 
Cardium serratum Reeve, Conch. Icon., it, pi. i,fig. 1, 1844. 
Shell subsolid, suboval or subquadrate, the posterior edge being less curved than the anterior; 
the low, rounded, posterior ridge being slightly produced at the base of the shell; surface nearly 
smooth, shining and polished, with only faint vestiges of ribs, which appear on the border of the shell 
which scarcely gapes and has delicate serrations within ; laterals high and strong; cardinals small; 
interior of the shell polished; in a fresh state the surface is usually covered with a thin, brownish 
epidermis; the shell is beautifully polished, whitish, straw-colored, lemon-yellow, purplish or reddish, 
and it is slightly clouded with brown near the beaks; within it has much the same range of colors, 
and it is one of the most delicate and lovely shells of the Antilles. 
Length, 37; height, 45; diameter, 30 mm. 
Vieques, a number of very fine specimens; Mayaguez, two young valves; Culebra, several young 
shells. 
Cardium (serratum var.?) sybariticum Dali. Plate 58, fig. 11. 
Cardium serratum var. sybariticimi Dali, Bull. Mus. Comp. Zool., Cambridge, xii, p. 271, 1886. 
Shell much smaller and more delicate than the type, more compressed, pale or faintly flecked 
with pink or purple; beaks often deep pink. 
Length, 11; height, 14; diameter, 7 mm. 
Mayaguez Harbor, Porto Rico, a number of dead valves. 
Cardium serratum var. laevigatum Lamarck. 
Cardium leevigatum Lamarck, An. sans Vert., pt. I, p. 11, 1819; not of Linneeus, 1758, nor of Born, 1780. 
Shell rather large, subsolid, moderately inflated, subquadrate, usually, though not always, faintly 
ribbed; ribs numerous when developed, strongest around the outer part of the shell; there is an area 
at the anterior and posterior parts of the shell which is generally smoother than the rest of it, which 
is outlined by a shallow groove, forming a sort of lunule and escutcheon; laterals rather strong, 
especially the anterior ones; edges of the shell serrated within. 
Color generally whitish, cream or pale buff, with a few faint subconcentric cloudings of brown. 
Length, 50; height, 63; diameter, 40 mm. 
One dead shell having the above measurements was taken at Playa de Ponce, Porto Rico. 
Generally larger, more quadrate, duller colored, and more painted with brownish, nebulous bands 
than typical serratum, yet there are intermediate specimens which can be assigned to one form about 
as well as to the other. This form is one of the characteristic species of west Florida. 
Cardium serratum var. multilineatum, n. var. 
Cardium lineatum Krebs, W. I. Marine Sh., p. 115, 1864; not of Gmelin. 
Smaller, more nearly round than the type. The smoother anterior and posterior areas are 
distinctly marked out and are tawny or buff colored; the rest of the shell is dirty straw colored, and 
