PANAMIC-PACIFIC PELECYPODA 177 



The ligament is internal; in the right valve the resilium is attached to a knob- 

 like process along the dorsal margin and in the left valve to a semilunate 

 scar under the beak. Surface smooth or radially wrinkled or striated. 



Anomia peruviana d'Orbigny Plate 24, figures 2-2f 



Anomia Peruviana d'Orbigny, 1846, Voy. Amer, Merid., vol. 5, p. 673. (Payta, Peru). — 



Philippi, 1850, Abbild. und. Besciireib. Conchylien, bd. 3, heft 8, p. 131, Anomia, 



Tab. 1, figs. 2, 3.— Hertlein and Strong, 1946, Zoologica, vol. 31, pt. 2, p. 68. 

 Anomia adamas Gray, 1849, Proc. Zool. See. London, p. 115.— Reeve, 1859, Conch. Icon., 



vol. 11, Anomia, pi. 3, fig. 15 Galapagos. 

 Anomia pacillus Gray, 1849, Proc. Zool. Soc. London, p. 117.— Reeve, 1859, Conch. Icon., 



vol. 11, Anomia, pi. 4, fig. 19 Tumbez. 

 ?Anomia laqueata Reeve, 1859, op. cit., pi. 4, figs. 18a, b. Hab. — ? 

 Anomia alectus Gray, 1849, Proc. Zool. Soc. London, p. 115 Guayaquil. — Reeve, 1859, 



op. cit., pi. 6, fig. 28. 

 Anomia hamillus Gray, 1849, Proc. Zool. Soc. London, p. 117. — Reeve, 1859, op. cit., pi. 



7, fig. 32 Bay of Caues, West Colombia (Cuming). 

 Anomia larbas Gray, 1849, Proc Zool. Soc. London, p. 117. Payta. — Reeve, 1859, Conch. 



Icon., vol. 11, Anomia, pi. 3, fig. 13. 



Shell of medium size (about 50 mm.), subovate to subcircular, the 

 length and height in a normal specimen about equal, but the valves are 

 usually irregular due to fixation. Texture thin to moderately heavy, sub- 

 translucent, the upper valve generally thinner and with a more micaceous 

 or pearly luster, the lower valve heavier and flatter. Surface of upper valve 

 smooth and concentrically wrinkled or marked with radial costae which 

 in some specimens may be quite strong and riblike. Color of upper valve is 

 white or in shades of light or dark coppery red or brown, the lower valve 

 mostly greenish except for the central area which is porcelain white. 



This Anomia is common at Paita and in the Bay of Sechura, its surface 

 smooth, undulate or with irregular radial costae, the color a silvery, trans- 

 lucent white to deep copper brown. The relative position of the adductor 

 scars in the upper valve have no specific valve as assumed by Dall. 



Range — Lower California to northern Peru and the Galapagos. 

 Ecuador: Manta; Santa Elena. Peru: Zorritos; Negritos; Paita; Sechura. 



Anomia fideuas Gray Plate 24, figures 4, 4a 



Anomia fidenas Gray, 1849, Proc. Zool. Soc. London, p. 116 Panama. — Reeve, 1859, 



Conch. Icon., vol. 11, Anomia, pi. 6, fig. 30 West Coast of Panama (Cuming). 

 Anomia tenuis C. B. Adams, 1852, Ann. Lyceum Nat. Hist. New York, vol. 5, pp. 469, 



544, No. 378 Panama. — Turner, 1956, Occasional Papers on Mollusks, vol. 2, 



No. 20, p. 91, pi. 18, fig. 13. 



Shell small or of medium size, suborbicular, flat, thin, smooth, or little 

 wrinkled, white or glassy. On the under surface of rocks. 



Range — Panama. Panama: Panama City. Canal Zone: Amador. 



Genus rODODESMTJS Philippi, 1837 



Type species by monotypy, Pododesmus decipiem Philippi (—P. rudis 

 Broderip), 



Like Anomia, but with a heavier shell and the right valve is attached 

 by its whole surface to the substratum as well as by the byssus. The byssal 

 foramen is closed by a vertical layered plug which is situated well within 

 the hinge margin; below it lies the single scar of the retractor muscle. 

 The interior of the left valve has two muscle scars. Surface smooth or covered 

 with fine, radial threadlets. Ligament attachment similar to that of Anomia. 



