386 ZOOLOGY. 



Family ANATINIDJ1. 

 MYTILIMERIA NUTTALLI. 



Mytilimeria nuttatti, CONE. Journ. Acad. Phila. VII, p. 247. pi. 19, f. 5. CARP. Rep. p. 301. 

 flat.- -San Diego; Lieutenant W. P. Trowbridge. 



A small group of this curious shell, nestling in a white friable arenaceous substance, was 

 received by the Smithsonian Institution through the kindness of Lieutenant Trowbridge. 



Family PHOLADIDAE. 

 PHOLAS PENITA. 



Pholas penita, CONR. Jour. Acad. Phila. VII, p. 237, pi. 18, f. 7, 1837. 

 Phdm concamerata, DESHAYES, Eev. Zool. p. 234, 1839. IDEM, Mag. de Zool. pi. 17, 1840. 

 Parapholas penita, CONK. Jour. Acad. Phila. 1849, p. 214, CARP. Rep. p. 290. 

 ffab. Shoalwater bay, Dr. Cooper ; Straits of Fuca, Dr. Suckley ; Oregon, mouth of Umpqua river, Dr. Vollum, U. S. A. 



"A specimen was obtained from a piece of worn rock which drifted into the bay attached 

 to the roots of macrocystis, the giant seaweed.' 1 C. 



