PLATE XXXVI. 
Pliocene Pectens. 
(All figures about two-thirds natural size.) 
Fig. 1. Pecten ( Patinopecten) caurinus Gould. Collection of Delos Arnold. Exterior 
of left valve; altitude 105 mm. Pliocene, Deadman Island, Los Angeles 
County. Specimens of this species measuring over 8 inches (200 mm.) 
have been found in the Pliocene of Ventura County. This form appears 
to be confined to the upper Pliocene and Pleistocene in southern Cali¬ 
fornia. Right valve more convex and with broader square ribs and 
plain concentric sculpture. 
Fig. 2. Pecten ( Chlamys ) latiauritus Conrad. Collection of Delos Arnold. Exterior 
of right valve; altitude 25 mm. San Pedro formation (Pleistocene), San 
Pedro, Los Angeles County. Known also from the lower Pliocene at 
Los Angeles. 
Fig. 3. Pecten ( Chlamys) latiauritus Conrad. Collection of Delos Arnold. Exterior 
of left valve; altitude 27 mm. Same locality as fig. 2. 
Fig. 4. Pecten ( Pecten) stearnsii Dali. U.S.N.M. 148008. Exterior of right valve; 
altitude 87 mm. San Diego formation (Pliocene), Pacific Beach, San 
Diego County. (See PI. XXXV, fig. 2, for left valve.) 
Fig. 5. Pecten (Pseudamusium) pedroanus Trask. U.S.N.M. 164840. Exterior of 
right valve and young left valve; altitude of former, 22 mm. Lower 
Pliocene, Third street tunnel, Los Angeles. Also found in beds of 
supposed Miocene age in the Puente Hills and San Pedro. 
Fig. 6. Pecten ( Pseudamusium) pedroanus Trask. U.S.N.M. 164840. Exterior of 
imperfect left valve; altitude 30 mm. Same locality as fig. 5. 
Fig. 7. Pecten ( Chlamys) parmeleei Dali. U.S.N.M. 154479. Type. Left valve; 
altitude 45 mm.; about five-sixths natural size. Pliocene, Pacific Beach, 
San Diego County. Also known in Pliocene of Puente Hills. 
Fig. 8. Pecten ( Chlamys) opuntia Dali. U.S.N.M. 107752. Type. Right valve; 
altitude 33 mm.; about four-fifths natural size. Pliocene, Pacific Beach, 
San Diego County. Also common in Pliocene at Santa Barbara and 
elsewhere in southern California. 
Fig. 9. Pecten ( Pecten) merriami Arnold. California State Mining Bureau. Type. 
Exterior of imperfect left valve; altitude 110 mm. Pliocene, Piru 
Creek, Ventura County. Characteristic of the lower Fernando horizon 
(lower Pliocene or upper Miocene) so far as known. Right valve convex, 
with broader squarer ribs. 
244 
