496 AXEL A. OLSSON 



EXPLANATION'' OF PLATE 23 



Figure Page 



1-la. Ostrea (Crassostrea) cortezlensis Hertlein 171 



Interior and exterior of a left valve, height 93.4 mm. Cathedral 

 Rocks, Panama City, Panama. Ptll 25614. 



2-2a. Ostrea ( ) iridesceng Gray 174 



Fig. 2, lower valve, height 134 mm. Caleto Sal, Peru. PRI 25615. 

 Fig. 2a, upper valve, height 130 mm. Cathedral Rocks, Panama 

 City. PRI 25616. 



3-3a. Ostrea (Alectryonia) megodon Hanley 172 



Length 94 mm. Bayovar, Peru. PRI 25617. 



4-4a. Ostrea (Crassostrea) columbiensis Hanley 172 



Inside and outside of lower valve, length 55 mm. Guayaquil, 

 Ecuador. Market. PRI 25618. 



5-5a. Ostrea (Alectryonia) palmnla Carpenter 173 



Fig. 5, he-ght 40 mm.; Fig, 5a, height 45 mm. Guanico, Panama. 

 PRI 26519. 



6. Ostrea (Alectryonia) fischer! Dall 173 



Height 125 mm. Gulf of California. 



7-7a. Ostrea (Alectryonia) palmnla Carpenter 173 



Guanico, Panama. PRI 25620. 



