148 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. 37. 
ANNOTATED LIST OF THE MOLLUSCA COLLECTED. 
ANOMIA PERUVIANA Orbigny. 
Plate 28, fig. 4. 
Anomia peruviana OrBIGNy, Voy. Amer. Mér., vol. 5, 1846, p. 673.—PHILIPPI, 
Abb. und Beschr. Neue Conch., vol. 3, 1850, p. 211, pl. 1, fig. 2. 
Anomia lampe GRAY, Proc. Zool. Soc. of London for 1849, p. 117.—R&Eve#, Conch. 
Icon., vol. 11, Anomia, 1859, pl. 4, fig. 16. 
Concha perla. Not ‘‘Concha de la Perla Viuda,’’ which is applied to Pteria, the 
pearl oyster. Common, sessile on oysters, etc., near Capon and Matapalo. 
Distribution.—From San Pedro, California, to Paita, Peru. 
Shell very thin, pearly; white or coppery brown on the upper 
valve, bluish green internally and on the central part of the lower .- 
valve; sessile on other shells or smooth objects adhering by a promi- 
nent byssus which passes through a large hole in the lower valve. 
The scars of the muscles in an area on the inside of the upper valve 
form a nearly even straight row radiating from the direction of the 
hinge. The species can be distinguished from the other local species, 
Anoma adamas Gray, by the fact that the latter has the two distal 
scars on the area side by side and about equidistant from the hinge. 
These shells have no economic relation unless it is that, when pres- 
ent in large numbers, they are injurious to the oysters upon which 
they perch, by consuming food the latter might otherwise get, or by 
overloading the oysters with their weight. 
The A. adamas Gray, has been collected in Sechura Bay, at Mata- 
caballa, but seems to be less common than A. peruviana. 
OSTREA MEGODON Hanley. 
Ostrea megodon HANLEY, Proc. Zool. Soc. of London for 1845, p. 106.—Sowrrsy, 
in the Conchologia Iconica, vol. 18, Ostrea, 1871, pl. 12, fig. 24. 
Taken in dredge, Bay of Sechura, about halfway between Bayovar and Matacaballa. 
Distribution.—From Scammon Lagoon, Lower California, and the 
Gulf of California, south to Peru. Fossil in the Antilles. 
This species is very thin, narrow, and ribbon like; the margin fluted 
by four or five broad rounded waves, the color pale brownish when 
fresh, bleaching to white when beach worn. It has no economic 
value. 
OSTREA CHILENSIS Philippi. 
Plate 26, fig. 1. 
Ostrea chilensis Puttrprt, Martini-Chemnitz Conch. Cab., 2d ed., Ostrea, 1845, p. 
74, pl. 18;:figs.:.7-8. 
Ostra of the fishermen. From the roots of mangroves, near the mouth of the Tumbes 
River. 
Distribution.—From the island of Chiloé northward to the coast of 
Ecuador. 
Shell ovate trigonal, irregular, moderately heavy; externally 
grayish white, internally white, sometimes faintly tinged with green; 
