290 ALLAX HANCOCK PACIFIC EXPEDITION'S VOL. 23 



PLATE 57 



Pecten (Oppenhr'imopecten) hancocki sp. nov. Hancock expeditions 

 station 780b-38, Chatham Bay, Cocos Island, Costa Rica, in 47 

 fathoms. Height: 47 mm; length: 49 mm. (Hancock Foundation 

 collection.) P. 



