114 TERTIAKY AND QUATERNARY PECTENS OF CALIFORNIA. 



1831. Pecten I'lalei Conrad, Aiiier. >lar. Conch., ji. 12, pi. 2, tig. 2. 



1836. Pecten Mandlca Muller, Lamarck, Anim. Saniri. Vert., ed. 2, vol. 7, y. 145, Xo. 42. 



1843. Pecten IsUmdicus Muller, Sowerby, Thea. Conch., vol. 1, Pecten, figs. 159-161. 



1844. Pecten Fabrlrii Philippi, Abbild. und Beschrcib. Concliyl., vol. 1, p. 101, pi. 1, fig. 5. 

 1853. Pecten Islaudictis Muller, G. O. Sars, Moll. Reg. Arcticre Norvegise, p. 16, pi. 2, fig. 2. 



1888. Pecten Islandicus Muller, Kiister and Kobelt, Conch. -Cab., vol. 17, pt. 2, Spondylus und Pecten, 



No. 24, p. 59, taf. 16, figs. 1 and 2. 

 1888. Pecten islandicus Chemnitz, Kiister and Kobelt, op. cit., p. 105, taf. 30, figs. 1-6. 

 1888. Not Pecten islandicus Cooper, Seventh Ann. Kept. Cal. St. Min., 1888, p. 257 ( = /'. jin-dnni 



Arnold, 1903). 



1897. (Jhliitiu/s islandica (Chemn. ), Verrill, Tians. Conn. Acad. Sci., vol. II), .June and .Tuly, 1S97, p. 



72, pi. 16, figs. 2-5/v pi. 20, fig. 9; pi. 21, fig. 2. 



1898. Pecten (Chkunys) isUindiciis Muller, Dall, Trans. AVagncr Free Inst. Sci., vol. 3, jjt. 4, p. 708. 

 1901. Ppc/«i i'«('a)wK("».s Miiller, Brcigger, Norges Geol. Undersi)gelse, No. 31, p. 228, fig. 23. tab, 5, figs. 



1, a, li, c, and d. 



Description. — Shell iiveragirig about 80 millimeters in altitude, .subcircular, 

 somewhat higher than hnig, subequivalve, both valves only .slightly eonve.x, equi- 

 lateral, excei)t for ears; of medium thickness; sides only slightly concave above; 

 base evenly rounded; color of living shell pinkish to salmon, the left valve being 

 tli(> more highly colored. Right valve with numerous narrow, square, flat-topped, 

 imbricated ridges, which multiply slowly, l)oth ))y division and intercalation, as the 

 shell grows; interspaces narrow, channeled, and minutely reticulated; hinge line 

 equal to more than one-half length of disk; anterior ear much produced, sculp- 

 tured by numerous sharp imbricating lines and 5 or (! major radiating ridges and 

 .some intercalaries; byssal notch quite prominent; potiterior ear a little over one- 

 half as long as the anterior, and sculptured in the same way. Left valve similar 

 to right, except possibly that the imbrication is a little more pronounced. 



Dimensions. — Alt. SSmm.; long. 77 mm.; hinge line 4-i mm. ; diameter L'7 nun.; 

 apical angle 84°. 



This species is (^laracterized by its large size when adult, large number of 

 subecjual scaly ribs, I'eticidated, channeled interspaces, and the relatively long- 

 posterior ear for a member of this group. 



Onl}' two authentic specimens of this species are known from California; 

 both are from the Pliocene of Deadman Island. San Pedro, one being in the Voy 

 collection at the University of (California and the othei- in the collection of Delos 

 Arnold. 



K.-INGE. 



Living. North Atlantic; Bering Sea (Dall). 



Pleistocene. Bowlder cla3's of the northwest American coast, Alaska, and British 



Columbia (Dall). 

 Pliocene. Deadman Island, San Pedro (Voy, Arnold). 



Pkcten (Chlamys) .jordani Arnold. 



PI. Xl.lV, figs. 1, lf(, and ]/-. 



1903. Pecten (clddvuis) junhini .\.rnold, :Mem. Cal. .Vcad. Sci., vol. 3, 1903, p. Ill, pi. 12, figs. 6 and 7. 



Descrijition. — Shell shape of I'. /■''/(ohUcus, averaging about 45 millimeters in 

 altitude, somewhat shorter than high, inequivalve, both valves convex, equilateral 



