MOLLUSOA OF PORTO RICO. 
467 
Family SPONDYLID^. 
Genus SPONDYLGS Linu*us, 1758. 
Shell irregular, inequi valve, attached by the right valve, which has a triangular area, auriculate, 
with radial, generally spinous or foliaeeous ridges; resilium in a central pit; hinge with two curved, 
interlocking teeth in each valve; adductor impression duplex. 
Spondylus echinatus Martyn. 
Ostrea echinata Martyn, Univ. Conch., n, fig. 154, 1784. 
Shell with four to eight radial spinose ridges, which are sometimes small and narrow or they 
may he large and foliaeeous; between the ridges are smaller ones, often hearing small spines, and 
in addition there is a third set of minute ridges, which are scaly and reticulated by the growth lines; 
lower valve often foliaeeous, especially on earlier growth; border of valves dentate, often edged with 
yellow, orange, scarlet, or purple. Interior sometimes delicately iridescent. Color whitish yellow, or 
orange, scarlet, or purple. In the lighter-colored shells the beaks are often richly colored. 
Length, 80; overall, 120; height, 90; overall, 120; diameter, 40; overall, 60mm. 
Boca Prieta; off Point Melones, Porto Rico. 
Genus PLICATULA Lamarck, 1801. 
Shell irregular attached by the beak of the right or left valve; valves plaited; hinge area obscure; 
resilium internal; right valve having a longitudinal cardinal on each side of the resilium and outside 
of these teeth a socket which receives the teeth of the other valve; muscular impressions single. 
Plicatula gibbosa Lamarck. 
Plicatula gibbosa Lamarck, Syst. An. sans Vert., p. 132, 1801. 
Plicatula vexittata Guppy, Geol. Mag. Dec., u, vol. i, p. 444, pi. xvn, fig. 7, 1874. 
Shell solid, irregular, somewhat fan-shaped, with strong, radiating, often divaricate plications, 
which end in serrations; whitish or brownish, commonly marked on the ribs with irregular, radiating, 
dark brown lines. 
Length, 25; height, 25; diameter, 10 mm. 
Aguadilla, Porto Rico, one valve. 
This is the well-known Plicatula ramosa of Lamarck, but the name gibbosa was applied by him to 
the same species previously. It is often gregarious, and a half-dozen specimens are sometimes found 
attached to a single shell or to each other. 
Family LIMIIbE. 
Genus LIMA (Bruguiere) Cuvier, 1798. 
Shell equivalve, compressed, white, obliquely oval, having rayed ribs or striae, auriculate; 
anterior side generally straight, gaping; posterior side rounded, usually closed; hinge area triangular, 
with a central resilium; muscular impressions lateral, duplex, large. 
Lima scabra Born. 
Ostrea scabra Born, Test. Mus. Vine!., p. 110, 1780. 
Lima scabra Sowerby, Conch. Icon., xviii, pi. n, fig. 8, 1872. 
Shell nearly equilateral, being but slightly oblique, the hinge line nearly horizontal, decidedly 
gaping and reflexed at the upper, anterior portion, nearly closed posteriorly; hinge area low, triangular; 
cartilage triangular; surface covered everywhere with fine, radiating ridges, which are prickly-scaly; 
edges of the shell serrate by the sculpture. Epidermis brown. 
Length, 45; height, 55; diameter, 17 mm. 
Aguadilla; Ponce; Mayaguez Harbor, Porto Rico; Ensenada Honda, Culebra. 
Lima scabra var. tenera Sowerby. 
Lima tenera Sowerby, Thes. Conch., p. 84, pi. xxi, figs. 10, 11, 1846. 
Shell subovate, subcompressed, thin, roughened with delicate scabrous ribs, which are somewhat 
interrupted; gaping anteriorly, the shell thickened at the opening. 
A smaller, more delicate and more finely ribbed form than the typical L. scabra. 
Mayaguez Harbor, Porto Rico, valves. 
