PLIOCENE PEGTENS. 113 



Pleistocctio. Ik)uider clav of Coiiiox. \'aiicoiiver Island (Newcomhe). 

 Pliocene. Deiidniiui Island, Siin Pedro (I):ill, .Stearns); Tinuns Point. San Pedro 

 (Arnold): Pacitic Heat'li, San Dicfj'o (Hamlin). 



Pi'.CTEN (ChlLAMYS) lIASTATi:S SoWKlUiV xar. STHATECIVS Dall. 

 I'l. XIJV, 2, LV, .■!, and 4. 



ISilS. I'liirn liericenx var. slmlcgus L)all, Trans. Wagner Free Inst. Sei., vol. :>, pt. 1, KSIIS, ]>. 709 

 190.S. IWtcii {Chlomi/s) hericeus var. stniti'(/iix Dall, Arnold, Mem. C'al. Acad. 8ei., vol. :-i, 1903, p. 

 110, pi. n, fijr. .5 (right valve of a younf^ .xpeeiiiien figured). 



I)ewrf'ptwn. — Adult, shell averaginj^' aVwut ii5 millinielcrs in altitude, sliolitly 

 hig-her than long, inequivalve, equilateral, except for ears: both valves nearly 

 fiat up to an altitude of about '2-2 niillinieters, where th(!V generally l)ec<)me more 

 convex i)\- eontraetion. and the sculpture Ijecomes more complicated. Right valve 

 with 9 to 12 prominent, subequal, broad, nearly flat-topped, usually dichotomous, 

 turgid ribs, with sonu^times smaller intercalai'v riblets, all of vvhicli l)reak up 

 more or less suddenly into fasciculi of two or more riblets iqjon reaching an 

 altitude of about 22 millimeters; interspaces .subequal, broad, and chaiuicled; 

 whole surface of disk' and ribs microscopically tessellated; hinge line equal to 

 about i)nc-half length of disk; anterior ear nuich pi-oduced, and scul])t.ui'ed 

 by fine imbricating incremental lines and about (1 radial ridges; byssal notch 

 prominent; iiosterior ear nearly obsolete, sculptured similarly to right. Left 

 valve resembling the right exc(^pt that the ribs arc narrower, more convex, and 

 with the intercalary riblets usually more inibiicated; interspaces broader than in 

 right valve; anterior eai- with about s imbricated ridges. (\)lor of recent specimens 

 bright scarlet. 



Dimension^). — Alt. 35 mm.: long. HI mm.: hinge line IT mm.: diameter LB 

 mm.; umbonal angle 83 mm. 



This variety is easily distinguished by its few l)road ribs, which increase in 

 number \(>ry rapidly both l)y division and intercalation after reaching an altitude 

 of al)out 20 millimeters. Some of the Pleistocene (lower San Pedro formation) 

 specimens from San Pedro retain a pinkish color. 



K.\xr,E. 



Living. LTnala.ska (Dall). 



Pleistocene. Alaska (Dall); Deadnian Island, San Pedro (Arnold); Path-hou.se 



Beach, Santa Barbara (Arnold). 

 Pliocene. Packards Hill, Santa Barbara (.1. H. Wilson ). 



Pecten (Chlamys) islaxdicus Miiller. 

 PI. XLV, fig..!. 1 and hi. 



1776. Ostrira Isktmlicus Miiller, Prodr. Zool. Dan., No. 2990, p. 248. 

 1778. Pedea cinnabariuu Born, Muh., p. 103. (Fide Dall, 1898.) 

 1780. Ostrea Islandica Miiller, Fabricius, Fauna Groiil., p. 415. 



1784. Pecten. Idandlcus Miiller, Chemnitz, Oniich., vol. 7, p. ;W4, pi. ft), figs, til.i and liKi. 

 1784. Pecten rubidm Martyn, Univ. Conch., vnl. 2. pi. 1.53, ijg. l. 

 1797. (hireii deiitiam Solander, Museum (^ilnnnianum, )>. .")2. Xo. 986. 

 17260— No. 47—06 8 



