528 axel a. olsson 



Explanation of Plate 55 



Figure Page 



1. Atriiia (Seratriiia) maura (Sowerby) 145 



Inside of a right valve showing the area covered by the nacreous 

 layer and the enclosed position of the posterior adductor scar. 

 Length 125 mm. Venado Beach, Panama Canal Zone. PRI 25776. 



2. Cyclinella subquadrata (Hanley) 263 



Length 92 mm. Bayovar, Sechura, Peru. PRI 25777. 



3-3a. Nioche (Jfloehe) metodon (Pilsbry and Lowe) 308 



Length 26.25 mm., height 23.8 mm., diameter 18.5 mm. El Lagar- 

 tillo, Panama. PRI 25778. 



4-4b. Chione (Chione) subimbricata (Sowerby) 295 



Figs. 4, 4a, length 42.4 mm. Venado Beach, Panama Canal Zone. 

 PRI 25779; Fig. 4b, length 35.2 mm. Pearl Islands, Panama. 

 PRI 25780. 



5. Colonche ecuadoriana, new species 311 



Length 49 mm. Puerto Palmito, Colonche, Ecuador. Holotype, 

 ANSP 218898. 



6. Jfioche (Nioche) zorritensis, new species 308 



Length 33 mm. Paita, Peru. 



7-7a. Petriocla (Faranio) botula, new species 317 



Fig. 1, length 12.5 mm., Paratype; Fig. lb, length 14.3 mm. 

 Holotype. Guanico, Panama. ANSP 218908. 



8. Petricola (Naranio) botula, new species 317 



Length 11.4 mm. Guanico, Panama. ANSP. 



9. Petricola (Petricola) peruTlana, new species 315 



Length 30 mm. Negritos, Peru. ANSP. 



10. Paphonotla elliptica (Sowerby) 312 



Length 35.7 mm. Negritos, Peru. PRI 25781. 



11. Petricola (Jfaranio) sp 317 



Length 16.3 mm. Esmeraldas, Ecuador. P'RI 25782. 



