MOLLUSCA OF PORTO RICO. 
491 
with a light grayish periostracum and some specimens a little rusty; posterior dorsal fold narrow 
and pronounced, but not very deep; surface covered with a fine dustlike granulation; the young 
proportionately more elongated, interior white, dull, with a polished margin outside the more or less 
broken and irregular pallial line; ligament elongated, brown, almost internal, set in a deep sulcus; 
resilium blackish, short, subumbonal, set on an obscure prominence on the hinge line in each valve, 
which, if the resilium were lost, would resemble obscure teeth; soft parts typical, with arborescent 
visceral appendages. 
Length, 6; height, 6; diameter, 3 mm. 
Off the entrance to San Juan Harbor, Porto Rico, in 310 fathoms, sandy mud, at station 6052. 
A well-marked species, easily discriminated by its form and surface from any other among the 
American species. See Dali, Synopsis of the Lucinacea, pi. xlii, fig. 2, 1901. 
Family LUCINIDtE. 
Genus CODAKIA Scopoli, 1777. 
Codakia orbicularis Linnaeus. 
Venus orbicularis Linnseus, Syst. Nat., ed. x, p. 688, 1758. 
Lucina tigerina Reeve, Conch. Icon., vi, pi. I, fig. 3,1850, not of Linnaeus, 1758. 
Shell large, suborbicular, rather solid, lenticular, with rather low but sharp beaks, which are 
turned forward over a small lunule, with a shallow, wide, radial posterior furrow and numerous 
radiating ribs or narrow, radiating furrows which cut the surface into ridges of different widths; the 
growth lines are elevated into fine, concentric ridges which leave the surface somewhat cancellated; 
ligament deeply inset; left valve with two radial cardinals and two low anterior laterals separated by 
a deep pit; right valve with two cardinals and a single anterior lateral; beak cavities rather deep, 
compressed; anterior muscle scars long, oblique; posterior scars oval; pallial line deep, crenated, disk 
rather rough, with numerous small pits. Color whitish or yellowish, often tinted with purple on the 
dorsal border, within white or yellow, often rich purple on the border, especially above. 
Length, 80; height, 70; diameter, 30 mm. 
Puerto Real, San Geronimo, Ilucares, Mayaguez, Porto Rico (Gundlach) ; West Indian region 
generally. 
A fine species very abundant on sandy bottom in shallow water throughout the West Indian 
region and in the Florida Keys. It is close to the East Indian O. tigerina, but is not so strongly 
cancellated or so nearly orbicular as is that species. 
Subgenus Jagonia Recluz, 1869. 
Codakia orbiculata Montagu. 
Venus orbiculata Montagu, Test. Brit. Suppl., p.42,1808. 
Lucina peeten Lamarck, An. sans Vert, v, p. 543, 1818; Reeve, Conch. Icon., vi, pi. x, fig. 38,1850. 
Shell suborbicular, inequilateral, compressed, rather solid, with sharp beaks, which are turned 
slightly forward over a large, indistinct lunule; ligament partly immersed, short; surface covered 
with numerous radiating ribs which are crossed by a large number of concentric finer ridges; these 
ridges sometimes form elevated scales where they cross the ribs, especially on the anterior and posterior 
portions of the shell; left valve with two radial cardinals, the anterior the larger, with two anterior 
and two posterior laterals; right valve with two cardinals, the posterior slightly bifid, with one anterior 
and one posterior lateral; beak cavities deep, compressed; anterior scars long, oblique; posterior scars 
oval; cavity of the shell rough, sometimes showing the ribbing of the shell; border crenate. Color 
whitish or yellowish. 
Length, 13; height, 12; diameter, 5.5 mm. 
Ensenada Honda, Culebra, one specimen. 
The beaks of this species are placed considerably behind the center of the shell, which is 
compressed and quite rough. 
Codakia portoricana Dali. 
Codakia ( Jagonia ) portoricana Dali, Synopsis of the Lucinacea, p. 822, pi. xxxix, fig. 6, 1901. 
San Juan Harbor, and the harbor of Mayaguez, Porto Rico. 
This inconspicuous little species appears to be rare and comes nearest to Jagonia costata d’Orbigny, 
than which it is more finely and evenly sculptured, besides being a more tumid and much smaller shell, 
measuring not over 8 mm. in length. 
