34 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 23 



as the southern limit in the Pacific. Hancock station BS2037, north of 

 Angel de la Guarda Island, increased the northern range in the Gulf 

 by about 330 miles ; Hancock station BS504, La Libertad, Ecuador, in- 

 creased the southern range by about 500 miles; Hancock station 155-34 

 established the first record from the Galapagos Islands. 



Geochronological range. Reported only from the Recent. 

 Bathymetric range: Recorded in 1 to 194 fathoms. Durham (1942, 

 p. 121) reported this species at E. W. Scripps station A3599, Sal Si 

 Puedes Channel, Gulf of California (between Lower California and the 

 San Lorenzo Islands), in 860 fathoms, ". . . in the mud, on a mushroom 

 anchor." Although he did not say whether the specimens were living or 

 dead, it is almost certain that they were not living at that great depth. 

 Ecological data: Usually found in mud bottoms, occasionally sandy 

 mud or sand ; sometimes associated with eel grass or weed. 



Hancock Expeditions Collecting Stations: 

 GALAPAGOS ISLANDS: off Tagus Cove, Albemarle Island; in 50- 



60 fathoms, rock, nullipores, bryozoa, sta. 155-34. 

 ECUADOR : La Libertad ; 3 fathoms, bottom sample 504. 

 COLOMBIA: 5 bottom samples; Port Utria to Gorgona Island; 12- 



60 fathoms. 

 PANAMA: 4 bottom samples; Secas Islands to Jicarita Island; 12-80 



fathoms. 

 COSTA RICA: Port Culebra; 3-15 fathoms, mud, sta. 253-34, and 



bottom sample 309. 

 MEXICO: Tenacatita Bay, Colima; 50 fathoms, bottom sample 217. 

 CLARION ISLAND, REVILLA GIGEDO ISLANDS, MEXICO: 



Sulphur Bay ; 53 fathoms, bottom sample 223. 

 GULF OF CALIFORNIA: 24 stations; San Francisco Island north 



to Angel de la Guarda Island; 1-125 fathoms, sand, mud. 

 GUADALUPE ISLAND, MEXICO: Melpomene Cove; 34-36 



fathoms, sta. 1919-49. 

 WESTERN LOWER CALIFORNIA: 7 stations; Punta Eugenia 



north to Cedros Island; 13-44 fathoms, sand. 



Gyclopecten exquisitus sp. nov. 

 Plate 12 



Shell very small, largest valve found measuring 6 mm in height and 

 length ; rather thin but opaque, inequivalve and inequilateral ; beaks 

 closer to posterior margin and protruding a little above; hinge line 

 nearly as long as disk. Right valve of low convexity and slightly smaller 



