30 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL, 23 



the southern limits; Hancock stations increased the northern range by 

 about 45 miles, as well as furnishing the first proof that this species also 

 lives in the Gulf of California. It seems reasonable to assume that it 

 actually lives along the entire Lower California coast to Cape San Lucas 

 and throughout the Gulf. 



Geochronological range: Recorded only from the Recent. 



Bathymetric range: Taken at Hancock stations in both lesser and 

 greater depths than previously recorded: 16 to 172 fathoms. 



Ecological data: Almost always found in mud, but occasionally in 

 sand. 



Hancock Expeditions Collecting Stations: 

 GULF OF CALIFORNIA: 16-20 fathoms, sand; sta. 566-36, bottom 



sample 279 (Tiburon Island). 

 SOUTHERN CALIFORNIA and SANTA BARBARA ISLANDS: 

 13 stations; 45-172 fathoms, sand or mud. Northern limit: San 

 Miguel Island ; 57 fathoms, bottom sample 1234. 



Cyclopecten cocosensis (Dall) 1908 

 Plate 9, fig. 2 



Pecten (Cyclopecten) cocosensis Dall, 1908, p. 405, pi. 6, figs. 1, 3. 

 "U.S.S. Albatross, station 3369, near Cocos Island, Gulf of Pan- 

 ama [lapsus calami, Cocos Island, Costa Rica], in 52 fathoms, 

 rocky bottom, temperature 62°. 2 F." 

 [non] Pecten (Cyclopecten) cocosensis Dall. Hertlein, 1935, p. 319, pi. 

 18, figs. 7, 8. = Pecten pernomus Hertlein (see that species, this 

 paper), non P. cocosensis Dall, fide Hertlein & Strong, 1946, p. 

 62. 

 Cyclopecten cocosensis (Dall, 1908). Keen, 1958, p. 72, fig. 134. "The 

 type locality is Panama Bay, in 52 fathoms, . . ." 

 Holotype: U. S. National IVIuseum. 



Type locality : Albatross station 3369, near Cocos Island, Costa 

 Rica, in 52 fathoms. 



Original description: Shell small, suborbicular, translucent whitish, 

 irregularly painted with opaque white, red, and ferruginous brown, in 

 lines, zigzags, or clouded patches ; there are also visible on the right 

 valve in some of the specimens whitish rays which would give the impres- 

 sion until the interior is examined that the shell belongs to the Prope- 

 amusium group; ears subequal, small, the anterior larger, in the left 

 valve elegantly minutely reticulated and at the hinge line adorned by a 

 series of small, close-set, short, sharp spines ; in the right valve the sculp- 



