132 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 23 



tion, is not an object identical with another, and, although Nodipecten 

 subnodosus is recognized as the eastern Pacific analogue of N. nodosus, 

 there are important and easily seen differences between them. As for 

 Dodge's opinion, even if conclusive evidence of migration could be 

 shown, A^. subnodosus is sufficiently restricted ecologically and stabilized 

 morphologically to be regarded as a distinct species. 



Geographical range: Western Lower California: Scammon Lagoon 

 to Cape San Lucas. Gulf of California to Negritos, Peru. 



Geochronological range: Pliocene, Pleistocene, Recent. 



Bathy metric range: Recorded from low tide to 60 fathoms. 



Ecological data: Found in shallow depressions in sand at low tide; 

 in deeper water on rock, sand or mud bottoms, associated with red 

 algae, nullipores, coralline and coral ; vermetids, bryozoans and barnacles 

 often commensal, 



Hancock Expeditions Collecting Stations: 



PANAMA: Secas Islands; 14 fathoms, nullipores, sta. 450-35. 

 CLARION ISLAND, REVILLA GIGEDO ISLANDS, MEXICO: 



32-57 fathoms, nullipores, sta. 136-34, 137-34. 

 GULF OF CALIFORNIA: 13 stations; 2-60 fathoms, rock, sand, 



mud, coralline, algae, nullipores. 

 WESTERN LOWER CALIFORNIA: 24-25 fathoms, gray-green 

 sand, sta. 1261-41d2. 



Nodipecten magnificus (Sowerby) 1835 

 Plate 44 



Pecten magnificus Sowerby, 1835, p. 109. "ad Insula Gallapagos . . . 

 in coral sand at a depth of six fathoms." ["Variat a"; bright red.] 

 "ad Insulam Platae, Columbiae Occidentalis [La Plata Island, 

 Ecuador] ... in coral sand in seventeen fathoms." ["Variat ft"; 

 brown, variegated with white patches.] — Sowerby, 1842, p. 65, 

 pi. 15, fig. 114. "The colour is bright red. Mr. Cuming's collection. 

 East Columbia." [lapsus calami; West "Columbia."] 



[rao/i] Pecten magnificus Gabb, 1873, p. 256. Santo Domingo District, 

 Dominican Republic, West Indies. "Oligocene of St. Domingo." 

 [= Pecten nodosus Linne, fide Dall, 1898, p. 717.] 



{non'\ Pecten subnodosus Sby. Stearns, 1893, p. 372. "James Island 

 Galapagos . . . The examples are from 1% to 2 inches high and 

 have twelve to fourteen ribs." [= P. magnificus.^ 



Pecten magnificus Sowb. Pilsbry & Vanatta, 1902, p. 550. "Tagus 

 Cove [Albemarle Island, Galapagos Is.] and Narbro [Narborough 

 Island, Galapagos] , opposite Tagus Cove." 



