MOLLUSCA OF PORTO RIOO. 
495 
Family DIPL0D0NT1D4}. 
Genus DIPLODONTA Bronn, 1831. 
Shell suborbicular, rather thin, white, concentrically striate, without a lunule; hinge with two 
cardinals in each valve, the posterior in the right and the anterior of the left bifid; lateral teeth 
wanting; muscular impressions oval, elongated; margins of the shell smooth. 
Section DIPLODONTA s. s. 
Diplodonta nucleiformis Wagner. 
Mysia nucleiformis Wagner, Journ. Acad. Nat. Sci. Phila., vin, p. 52, pi. I, fig, 4, 1838. 
Cytherea sphserica H. C. Lea, Trans. Am. Phil. Soc., 2d series, ix, p. 241, pi. xxxiv, fig. 22, 1845. 
Mayaguez Harbor, Porto Rico, at station 6062, in 30 fathoms, sand, and off Culebra Island. Also 
at St. Thomas and northward to the vicinity of Cape Hatteras, North Carolina, in 15 to 52 fathoms; 
fossil in the Miocene and upper Oligocene of the eastern United States. 
Section PHLYCTIDERMA Dali, 1899. 
Diplodonta notata, n. sp. 
Shell suborbicular, with rather high, nearly central beaks, scarcely inflated; surface with very 
delicate growth lines, minutely pitted throughout excepting in the umbonal region; left valve with 
two cardinals, the hinder compressed, the anterior triangular and deeply bifid; right valve with the 
hinder tooth bifid and the anterior compressed; ligament almost wholly internal, narrow; muscle scars 
somewhat elongated; interior rather smooth. Color white. 
Length, 9; height, 8.5; diameter, 3.5 mm. 
Mayaguez Harbor, Porto Rico, one pair and a single valve. It ranges from Marc'.o, Florida, south 
to Porto Rico. 
Diplodonta puncturella Dali. 
Diplodonta puncturella Dali, Trans. Wagner Inst., in, p. 1183, pi. xlv, tig. 26, 1900. 
San Juan Harbor, Porto Rico; also Jamaica. 
Family CHAMID 2 E. 
Genus CHAMA (Linnaeus) Lamarck, 1799. 
Shell attached, irregular, inequi valve, thick; beaks spiral or subspiral, that of the fixed valve 
always the longer; surface lamellated; the free valve operculiform, slightly convex, sometimes right 
and sometimes left; hinge thick, bearing an anterior groove, an oblique, arched cardinal, and an 
oblique, straight furrow; fixed valve more convex and larger than the other; hinge plate thick, with 
one strong anterior cardinal and a curved posterior tooth ; border of the valves crenated. 
Chama macrophylla Gmelin. 
Chama macrophylla Gmelin, Syst. Nat., p. 3304, 1792; Chemnitz, Conch. Cab., VII, p. 149, pi. lii, figs. 514, 515. 
Quebradillas, Porto Rico (Gundlach). 
Chama sarda Reeve. 
Chama sarda Reeve, Conch. Icon., iv, pi. vii, fig. 40, 1847. 
Shell small, somewhat orbicular; attached valve deeper than the free one, irregular; surface 
bearing subconcentric rows of wavy scales, white, clouded with brown and white, crimson and white, 
or crimson, the upper valve often having curved radiating rays of red on a white ground; ligament 
short, curved; left valve with an anterior tooth, behind which is a pit; right with an anterior pit and 
behind it a tooth; teeth blunt and rounded; beak cavity of the lower valve deep, that of the upper 
valve often deep; muscle scars rather long; border faintly crenate. 
Length, 27; height, 30; diameter, 23 mm. 
San Geronimo, Mayaguez, San Juan, Porto Rico; Vieques; mostly young and worn valves. 
This species is much smaller than C. macrophylla, and may generally be distinguished by its 
different and often beautiful color patterns and the crimson and white staining of the free valve. 
