148 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. S7. 



ANNOTATED LIST OF THE MOLLUSCA COLLECTED. 



ANOMIA PERUVIANA Orbigny. 



Plate 28, fig. 4. 



Anomia peruviana Orbigny, Voy. Amer. Mer., vol. 5, 1846, p. 673. — Philippi, 



Abb. und Beschr. Neue Conch., vol. 3, 1850, p. 211, pi. 1, fig. 2. 

 Anomia lampe Gray, Proc. Zool. Soc. of London for 1849, p. 117. — Reeve, Conch. 

 Icon., vol. 11, Anomia, 1859, pi. 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 nmscles 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, 

 Anomia 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. — Sowerby, 

 in the Conchologia Iconica, vol. 18, Ostrea, 1871, pi. 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 Philippi, Martini-Chemnitz Conch. Cab., 2d ed., Ostrea, 1845, p. 

 74, pi. 13, figs. 7-8. 

 Ostra of the fishermen. From the roots of mangroves, near the mouth of the Tumbes 

 River. 



Distribution. — From the island of Chiloe northward to the coast of 

 Ecuador. 



Shell ovate trigonal, irregular, moderately hea\^'; externally 

 grayish white, internally white, sometimes faintly tinged with green; 



