530 axel a. olsson 



Explanation of Plate 57 



Figure F'age 



1-la. Mactra (Mactromeris) dolabrifonnis (Conrad) 323 



Fig. 1, enlargement of the hinge of the right valve; Fig. la, exterior 

 of a small right valve, length 60 mm. Concepcion Beach, near 

 Las Tablas, Panama. PRI 25789. 



2-2b. Mactra (Micromactra) angnsta Deshayes 325 



Fig. 2, enlargement of the hinge of a right valve; Fig. 2a, inside 

 view, length 53.7 mm.; Fig. 2b, outside view, length 46.4 mm. 

 Punta Blanca, Ecuador. PRI 25790. 



3-3a. Labiosa anatina (Spengler) 333 



Fig. 3, enlargement of hinge; Fig. 3a, a fragmentary specimen, 

 length 41.8 mm. Santa Elena, Ecuador. PRI 25791. 



4-4a. Jttactra (Micromactra) fonsecana Hertlein and Strong 324 



Right and left valves, length 50.5 mm. Palo Seco, Panama Canal 

 Zone, PRI 25792. 



5. Mactra (Micromactra) vanattae Pilsbry and Lowe 325 



Length 32.5 mm. San Miguel, Rey Island, Pearl Islands, Panama. 

 PHI 25793. 



6-6a. Mactra (Micromactra) califomica Conrad 324 



Right and left valves, length 33.2 mm. Anaheim Bay, California. 

 CoU T. Burch. PRI 25794. 



7-7c. Spisala adamsi, new species 326 



Fig. 7, enlargement of hinge; Figs. 7a, 7b, 7c, length 36.2 mm. 

 Palo Seco, Panama Canal Zone. Holotype, ANSP' 218917. 



8-8d. fflcromactra 324 



A group of Micromactra to show undulations on the beak and 

 general shape. Copied after Pilsbry and Lowe, 1932, fig. 8. 

 Mactra vanattae acymata Pilsbry and Lowe; Fig. 8a, Mactra 

 califomica Conrad; Fig. 8b, Mactra angusta Deshayes (fonsecana 

 Hertlein and Strong) ; Fig. 8c, Mactra vanattae Pilsbry and Lowe; 

 Fig. 8d, Mactra isthmica Pilsbry and Lowe. 



