110 CAUKLtSXU ACAPEMY OP SCIENOK. 



a8. Pecten vChlamyst hericeus Gomld. 

 fixn II. Fks. S. 



fifttem Miriams Glol. Ptoc Bost Soc Nat. Hist.. VoL III. 1S50. p. 345; Wilkes Expl. Exped.. 



Vol. XII. 1852, Pl 457. fig. 570. Dall. Trans. Wagner Inst. Sci., Vol. Ill, Part 4, 



1S9S, p. 708. 

 Petien htsMims of Carpexter. Brit. Assn. RepC, 1S63. p. 645 (not of Sowerby, Thes. Conch., 



1S43). ? Gabb. PaL CaL. VoL II. 1S69. p. 104. ? Cooper, 7th Ann. Rept. CaL St. 



Min.. iSSS, PL 257. 



SheO of mediam size. tiiai^;ular ovate, compressed, equivalve. thin; surface of left valve 

 sculptured by aboat fourteen to sixteen groups of tasciculated ribs, the groups being more prominent 

 and coatainii^ more ribs as the middle of the shell is approached ; the surface of all the ribs 

 roughened by numerous rather small, erect, arched spines; right \-alve nearly the same as left : 

 anterior car o( left valve large, acutely pointed with seven to dght sharp, squamosely striated 

 radiatii^ r" - ' ' r : ears of right \-alve the same except that a deep bj-ssal 



noccfa separ ^ of umbo rise abrupdy from ears. 



Dimiemsi^ns. — Long. 40 mm.; alt. 47 mm.: diam. 12 mm.; hinge 19 mm. 



This species r^embles P. hastatus in shape and general characteristics. In 

 P. Ikastatus there are seven to ten strong, narrow, prominent ribs, coarsely spinose, 

 while in P. I ' he ribs occar in fourteen to sixteen fasciculi, each fascicle con- 



sisting of ihrtv. .. : our nearly equally prominent, finely spinose ribs, and forming a 

 convex ridge. Specimens identitied by Dr. Dall. 



Rare in Pliocene of Deadman Island. The specimen figured is from that 

 horizon and is now in the collection of Delos Arnold. Found rarely in the Pliocene 

 of Pacific Beach, San Diego. 



Liring. — Straits of Faca (Goald): ? Sitka to Santa Barbara (Cooper). 



pi- . — gju Diego (Dall): ?Santa Barbara to San Diego (Cooper): San 



Pednj (A 



Pliocene. — San Pedro (Arnold): ? Santa Barbara; San Fernando; San Diego 

 well (Cooper): San Diego (Arnold). 



29. Pecten (Chlamys) hericens var. strategus DaU. 



PLiiE \L, Fig. 



3. 



PecUm kericnu var. stralegus Dalx., Trans. Wagner Inst. S<i, VoL III, Part 4, 1898, p. 709. 



Shape and general terture same as P. hericeus. " The &sdculi of the left valve, to the 



- of fire to seven, with the riblets coakscent, forming large, smooth-backed, turgid ribs, with 



' —'-- ---^ ■-■-^--'.'ary threads. The large ribs sometimes break up suddenly into the usual 



ie. The recent specimens are bright scariet." (Dall). The right valve of a 



' -'.and shovs nine fasdcnli, most of which seem to be made 



-^ .. . - . — .:.Lality to the umbo, instead of coalescing; the interspaces 



are slighdv ^!i. The anterior ear of this right valve is prominent and 



r'evated lines of growth; byssal notch 

 :, „_ _ke sculpture. 

 D- .18 nun.; alL 2i nun.: diam. 3.2 mm.; hinge 9.4 nun. 



