EXPLANATION OF PLATE 8 



All figures approximately natural size 



Fig. 1. Cryptomya quadrata Arnold. Eight valve; from locality 3005, Priest 

 Valley, Monterey County. 



Fig. la. Cryptomya quadrata Arnold. Left valve; from same locality as 

 figure 1. 



Fig. 2. Peeten etchegoini Anderson. Eight valve; from locality 3004, Priest 

 Valley, Monterey County. 



Fig. 2a. Pecten etchegoini Anderson, or P. etchegoini nutteri Arnold. Eight 

 valve of an intermediate form; from locality 3004. 



Fig. 2b. Pecten etchegoini nutteri Arnold. Eight valve; from locality 3004. 



Fig. 3. Macoma vanvlecJci Arnold. Eight valve; from locality 2526, Jaca- 

 litos Creek, Fresno County. 



Fig. 3a. Macoma vanvlecki Arnold. Left valve; from locality 2526. 



[246] 



