100 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 23 



ly white, but colored in varying degree with red, purple or brown; left 

 valve pale brown to black-brown, but white along ventral margin. 



Remarks: There is nothing in Sowerby's description of Pecten 

 ventricosus that would separate it from certain specimens of Chlamys 

 circularis; this species is certainly variable in convexity, obliquity and 

 sculpture, but nowhere within its geographic range are found variations 

 of either specific or subspecific importance. 



Geographical range: Cedros Island, Lower California, Mexico, and 

 the Gulf of California, to Paita, Peru ; Galapagos Islands. Specimens 

 taken at three Hancock stations accounted for the first Recent records 

 of this species from the Galapagos. 



G eochronological range : ?Pliocene, Pleistocene, Recent. 

 Bathy metric range: Recorded in 4 feet to 75 fathoms. 

 Ecological data: Found on rock, gravel, sand, sandy mud or mud 

 bottoms ; associated with kelp, corallines or gorgonians. 



Hancock Expeditions Collecting Stations: 

 GALAPAGOS ISLANDS: 5-70 fathoms, sand and rock; sta. 173-34, 

 183-34, 187-34 (South Seymour I.; between Albany and James 

 Is. ; Albemarle I.). 

 ECUADOR: 2-10 fathoms, sand and rock; sta. 23-33, 209-33, 211-33, 



217-33. 

 PANAMA: 2-15 fathoms, sand and rock; sta. 113-33, 251-34, 448-35, 



959-39, 960-39. 

 COSTA RICA: l>^-30 fathoms, sand and mud; sta. 116-33, 253-34, 



257-34, 469-35, 472-35, 478-35, 963-39. 

 WESTERN MEXICO: 5-20 fathoms, gravel, sand, mud; sta. 259-34, 



765-38, 927-39. 

 GULF OF CALIFORNIA: 37 stations; 3-70 fathoms, sand and mud. 

 WESTERN LOWER CALIFORNIA: 15-24 fathoms, sand; sta. 

 617-37, 1031-40d2, 1037-40. 



Chlamys (Argopecten) circularis aequisulcata (Carpenter) 1864 



Plate 33 



Pecten (fventricosus, var.j aequisulcatus Carpenter, 1864, p. 536. 

 [No?nen nudum.] "Of these forms . . . the diagnoses are written, 

 and will probably appear in one of the scientific periodicals for 

 1864." Footnote: ". . . presumed . . . from the neighbourhood of 

 Sta. Barbara." 



Pecten v. aequisulcatus Carpenter, 1864, p. 540. [No7nen nudum-] 

 "Near San Pedro." 



