PLATE X L \'. 



I'LIilCK.NK AXl) grATEKXAUY I'KCTKNS. 



[['iili'ss iillirrwisc stated nil ligiircs aiv iipiiroxiniatrly iiMlnnil .-izu.l 



Pase. 



Fici. 1. I'rrlcn ( Clihninix) ixluiiiliciin :\I tiller. 1>. A - H'' 



Exteriiir of i-i>r|it valve: altittide S8 niiii. Keeent, RaiikM of NewlDiiii'llan.l. (-A1. I>. ) 



Fk;. I'l. Same s|HM'iiiieii as Iilt- 1 - ^1'^ 



Exterior of left valve. ( M. I'.. ) 



Km. 2. Pi:.-I,,i {Ch/ininis) irfislilfiiniri n. ^\K E. S. X. :\I. l(i4S4:i. Type Hi* 



Exterior of iiii|ierfect li-ft valve; altituile KIS iiiiii. Plioeeiie, iiumtli of Yaehate.s River, 

 Lineohi Cmiity, < )re^'. (.M. I".. ) 



Fiti. 3. Pedcii (Vlilaiiiiix) htirsniil n. f[f. V. A. fi. Type 11" 



Exterior of riiiht valve ( iiiiiboand ears missing); longitude 65 iiiiii. IMioc-ene, 4 iiiiles sontli 

 of Guadalupe, Santa Barbara Coiinty, Cal. (S. ) 



Fig. 4. I'ccteii i'_'Iilini(!ix) lairmiii n. >^]k ('. A. S. ( 'otype 11" 



Exterior of an iiiiperfi'cl Ic^ft \alve in which the iinibonal region has been ]>artially 

 restoied with plaster; hjngitude o4 nun. Same locality as lig. :!. (.M. l'>. ) 

 284 



