COMPLETE GRAU : PECTINIDAE OF THE EASTERN PACIFIC 147 



Patinopecten caurinus (Gould 1850). Fitch, 1953, p. 44, fig. 10. 

 Wrangell, Alaska, to Eureka, California. 



Holotype: Museum of Comparative Zoolog>', Harvard College. 



Type locality: Port Townsend, Admiralty Inlet, Puget Sound, 

 Washington. For explanation of Gould's designation "Oregon" see 

 Type locality for Chlamys hastata hericea (Gould), this paper. 



Original description: T. trigono-orbicularis, haud crassa, inequi- 

 valvis, sub-equilateralis ; valva superior convexiuscula, rubra, striis con- 

 centricis tenuibus insculpta, costis humilibus rotundatis vel interdum 

 sub-duplicatis ad 20 ornatis ; valva inferior convexa, alba, versus mar- 

 ginem rubricans, radiis ad 22 elevatis, quadratis, longitrorsum striatis ; 

 natibus rosaceis compressis; auribus transversis, sub-equalibus, radiatim 

 striatis: intus lactea, rosaceo fimbriata. Long. 2% ; lat. 2]/^ ; alt. 1 poll. 



Additional description : Shell large, average adult specimens meas- 

 uring 150 mm in altitude, slightly oblique, inequivalve and compressed; 

 auricles nearly equal. Right valve larger than left and having 18 to 22 

 squarish flat-topped ribs which occasionally show faint radial striae 

 and /or longitudinal ridges ; interspaces flattish and becoming wider 

 toward ventral margin ; fine concentric growth lines covering disk. 

 Posterior auricle flat, with perpendicular margin and strong incremental 

 lines: anterior auricle rather narrow, with faint (often obsolescent) 

 radial ridges, sharp incremental lines and a prominent convex fold next 

 to the disk ; byssal notch moderately deep and no ctenolium. Left valve 

 smaller than right and slightly less convex; 18 to 22 low and gently- 

 rounded ribs ; fine concentric lamellae covering disk. Posterior auricle 

 having strong incremental lines and sometimes faintly ridged ; anterior 

 auricle having an oblique margin, a prominent concave fold and strong 

 incremental lines. Right valve yellowish-white to golden-brou-n ; left 

 valve usually pale to deep brown, rare specimens being red-brown or 

 purple. 



Remarks: The holotype was a young shell. In 1918 W. J. Eyerdam 

 dredged a specimen outside of Wrangell Narrows, Alaska, having some 

 of the ventral margin broken ofif but still measuring 288 mm in length 

 and 198 mm in height, the largest so far recorded. 



The Japanese subspecies Pecten caurinus yessoensis (Jay) differs 

 from P. caurinus in the following respects: right valve considerably 

 more convex, auricles higher and longer, byssal notch much less pro- 

 nounced and fine tessellate sculpture on left valve. 



Geographical range: Channel Inlet, Orca Inlet, Cordova, Alaska, 

 to Point Reyes, California. 



