PLEISTOCENE PECTENS. 131 



Pecten (Chlamys) latiauritus Conrsid var. fucicolus Dall. 



PI. XLVI, ligs. 8 and 8r(. 

 189S. F'lTlen Idllaiuiltix var. fuclcohu Dall, Trans. Wagner Free Inst. Sei., vol. ^, pt. 4, 1898, p 710. 



IMfcr//>tian. ^SheW of ^^illlle jjoneral type as J', latimiritm. Moderateh' com- 

 presspd. smooth, concentric sculpture obsolete; riV)s low, rounded, wide, entire; 

 hinge line .shorter than in the type, and witliout any sinus between the posterior 

 ear and the disk. 



JJiiiie/i«/on.s. — Alt. 80 mm.; long. 31 mm. 



"This form lives attached by the byssus to the giant kelp of the Californian 

 coast, and the absence of shock, due to the floating situs, is probably correlated 

 with the obsolescence of the ribs and the posterior sinus. Intergradations with 

 the type are not at all I'are." (Dall, 1898.) 



RANGE. 



Living. Santa Barbara, south to Cape St. Lucas (Dall). 

 Pleistocene. San Pedro; San Diego (Dall; Arnold). 



Pecten (Chlamys) latiauritus Conrad var. monotimeris Conrad. 



PI. XLVI, figs. 4, .5, and ha. 



1837. PeHen monotimeris Cfmrad. Jour. Acad. Nat. Sd. Phila., vol. 7, 1837, p. 233, pi. 18, tig. 10. 



1803. Pecten monotimerif Courad, Carpenter, Brit. Assn. Kept., 1863, p. 64.5. 



1888. Pecten monotimeris Conrad, Kiister and Kobelt, Coneh.-Cab., vol. 17, pt. 2, Spondylus un<l Pecteu, 



No. 2.57, p. 276, taf. 72, figs. 7 and 8. 



1888. Pecten latiauritus Conrad, Cooper, Seventh Ann. Kept. Cal. St. Min., 1888, 'p. 257 (in part). 



1892. Pecten monotimeris Conrad, Keep, West Coast Shells, 1892, p. 167, fig. 140. 



1897. Pecten { Leplopecten) immolimeris Conrad, Verrill, Trans. Conn. Acad. Sci., vol. 10, p. 69. 



1898. Pecten latiauritus var. monotimeris Conrad, Dall, Trans. Wagner Free Inst. Sci., vol. 3, pt. 4, 1898, 



p. 709. 



1903. Pecten (Chlami/s) latiaiiritu.'i Con. var. monotimeris Conrad, Arnold, Mem. Cal. Acad. Sci., vol. 3, 



pt. 2, 1903, p. 112, pi. 12, figs. 4 and 4a. 



1904. Pecten latiauritus var. monotimeris Conrad, Keep, West Am. Shells, p. 40, fig. 20. 



Description. — Shell of the general type of /'. lutlauritu.^, but more oblique, 

 inflated, and markedly shorter, with smaller ears; ribs generally prominent and 

 squarish, and interspaces deeply channeled; incremental sculpture sometimes very 

 pronounced. 



Dimensions. — Alt. -iOmnL; long. 19 muL; hinge line Iti nun.; diameter 9 mm. 



This variety i.s characterized by its ventricosity, well-detined ribs, and rela- 

 tively short disk and hinge line. /'. var. inonofimeris is very common at Los 

 Cerritos Hill, near San Pedro, but is nuich rarer in the other Pleistocene locali- 

 ties than the typical /'. l(ifi<(Kriti(.-<. 



Found in the fossil state in the upper San Pedro formation (Pleistocene); also 

 occurs recent. 



RANGE. 



Living. Fort Point, San Francisco (Button); Santa Barbara to San Diego (Dall). 

 Pleistocene. Santa Barbara; San Pedro (Dall); San Pedro; San Diego; Ventura 

 (Arnold); Newport, Orange County (No. 11895, C. S. M. B.) (Watts). 



