panamic-pacific pelecypoda 529 



Explanation of Plate 56 



Figure Page 



1. Mactrellona clisea (Dall) 328 



An enlargement of the hinge of the left valve and the exterior 

 of a right valve, length 83.4 mm. San Pedro, Ecuador. PRI 25783. 



2. Mactra fragills Linn§ 



Enlargement of the hinge of a left valve; the small symbols have 

 the following meaning, -e, scar of the external ligament, -r, 

 resilifer or chondrophore,-c,-shaped cardinal tooth, -1, lateral teeth. 

 Dominican Republic, West Indies. PRI 25784. 



3. Tnmbeziconcha thracoides (Adams and Reeve) 333 



Enlargement of hinge and exterior of a right valve, length 40 mm. 

 Tumbez, Peru. PRI 25785. 



4. Mactrellona alata (Spengler) 327 



Enlargement of hinge and exterior of a right valve, length 40 mm. 

 Bucaro, Panama. PRI 25786. 



5-5b. Harrella elegans (Sowerby) 329 



Fig. 5, enlargement of the hinge of a right valve; Fig. 5a, left 

 valve, length 53.3 mm.; Fig. 5a, dorsal view. Tumbez, Peru. PRI 

 25787. 



6-6b. Raeta undulata (Gould) 332 



Fig. 6, enlargement of the hinge of a left valve; Fig. 6a, exterior 

 of a right valve, length 51 mm.; Fig. 6b, a portion of the surface 

 magnified. Tumbez, Peru. PRI 25788. 



