COMPLETE GRAU : PECTINIDAE OF THE EASTERN PACIFIC 45 



of the right valve) and the wide angle formed by the lateral margins of 

 the posterior auricles and the hinge line. Specimens from the Santa 

 Barbara Islands and southward are usually more circular and of greater 

 convexity. Very young specimens may be difficult to distinguish from 

 Cyclopecten vancouverensis of similar size, but the latter are always 

 sculptured to some degree. 



The author examined a specimen in the Stanford University collec- 

 tion that Mrs. Oldroyd had labelled Pecten whiteavesi; it is identical 

 with southern California specimens of Cyclopecten randolphi. 



Geographical range: Bering Sea to Guaymas, Mexico (Gulf of 

 California). 



Geochronological range: Recent only. 



Bathymetric range: 10 to 1064 fathoms. 



Ecological data : Found on mud bottoms. 



Cyclopecten (Delectopecten) randolphi tillamookensis 



(Arnold) 1906 

 Plate 17 



Pecten (Pseuda?nusium) randolphi Dall van tillamookensis Arnold, 

 1906, p. 139, pi. 48, figs. 3, 3a. "From north of Unalaska, 351 

 fathoms, to off Tillamook Bay, Oregon, at United States Fish 

 Commission Station 3346, at a depth of 786 fathoms." 



Pecten (Pseudamusiu7n) arces Dall, 1913, p. 592. "Off Santa Barbara, 

 California, in over 500 fathoms, muddy bottom." [Albatross sta- 

 tion 4425, in 1084-1100 fathoms.] 



Pecten (Pseiidamusium) tillamookense Arnold. Dall, 1921, p. 20. 

 Pribiloff Islands, Bering Sea, to San Diego. 



Pseudamusium arces Dall. Dall, 1925a, p. 24, pi. 27, fig. 4. Off Santa 

 Cruz Island, California, in 534 fathoms. 



[non] Pecten (Pseudamussium) pedroanus (Trask). Grant & Gale, 

 1931 [ex parte], p. 236. [P. randolphi tillamookensis Arnold in 

 synonymy.] 



[non] Pecten (Pseudamussium) pedroanus (Trask) variety van- 

 couverensis Whiteaves. Grant k Gale, 1931 [ex parte], p. 238. 

 [P. arces Dall in synonymy.] 



Pecten (Pseudamusium) randolphi var. tillamookensis Arnold. Wood- 

 ring, 1938, p. 37. ". . . Bering Sea to San Diego, generally in deep 

 water (30 to 1084 fathoms)." 



Pecten (Delectopecten) randolphi tillamookensis Arnold. Proc. Conch. 

 Club So. Calif., 1944, no. 35, p. 14a. 



