PANAMIC-PACIFIC PELECYPODA 4fi3 



Museum. P. stearnsii has been recorded from the Pliocene of Burica Penin- 

 sula of Panama. 



Range — Gulf of California questionably southward to Panama. 



Feriploma (Periploma) planiasenla Sowerby Plate 82, figures 2-2e 



Periploma planiuscula Sowerby, 1834, Proc. Zool. Soc. London, p. 87 Sanctam Elenam. 



— Hanley, 1842, Rec. Bivalve Shells, p. 21, Appendix, p. 339, pi. 10, fig. 33.— 



Maxwell Smith, 1944, Panamic Marine Shells, p. 54, fig. 702. 

 Periploma lenticularis Sowerby, 1834, op. cit., p. 87 Isla Muerto. 

 Periploma argentaria Conrad, 1837, Jour. Acad. Nat. Sci. Philadelphia, vol. 7, p. 238, 



pi. 18, fig. 8 California. 

 Periploma obtusa Hanley, 1842, List of Illustrations to Lamarck Shells, t. 2, fig. 50. — 



Hanley, 1842, Rec. Bivalve Shells, Appendix, p. 339, pi. 13, fig. 50 West 



Colombia. 

 Periploma excurva Carpenter, 1855, Proc. Zool. Soc. London, p. 229. 

 Periploma excurvata Carpenter, 1857, Brit. Assoc. Adv. Sci., Rept. p. 287, (error for 



excurva ) . 



Shell of medium size (length up to about 57 mm.), elongately ovate, 

 thin, fragile, pearly, the right valve convex, the left with slight convexity to 

 flattened, depressed. The posterior side is much shorter, somewhat flexuous, 

 and generally truncated at the end. Surface usually cream-colored with a 

 dull luster and minutely pustulate or wrinkled over the whole disk, more 

 coarsely so on the posterior slope so that this area may appear somewhat 

 chalky. Interior shiny, pearly, the pallial sinus distinct but short. 



This is a common and widely distributed species, along sandy beaches, 

 from southern California to northern Peru. The shell shows considerable 

 variation in relative height to length. Californian specimens are heavier than 

 those from localities further south. 



Well-preserved shells have a slightly wrinkled surface, like that of 

 leather, the extremely small pustules arranged so as to form slightly ir- 

 regular, concentric lines. 



P. lenticularis, an unfigured form, described from the Isla del Muerto 

 in the Gulf of Guayaquil is believed to represent the same species. Its type 

 has not been seen. 



Range — Southern California to northern Peru. Panama: Bucaro; 

 Guanico. Colombia: Isla del Gallo. Ecuador: Mompiche; Sua; Santa Elena. 

 Peru: Tumbez; Boca Pan; Negritos. 



Feriploma (Periploma) teevani Hertlein and Strong Plate 83, figure 9 



Periploma teevani Hertlein and Strong, 1946, Zoologica, vol. 31, pt. 3, p. 95, pi. 1, figs. 

 2, 6 Tangola-Tangola Bay, Oaxaca, Mexico, 30 fathoms. 



According to its author, this species resembles P. planiuscula but 

 differs by its higher valves, shorter and wider rostrum and in having the 

 pustules arranged along radial lines. 



Range — Coast of Mexico. 



Periploma (Periploma) lagartilla, new species Plate 82, figures 5-5b 



Shell small or of medium size, thin, white to subtranslucent, obliquely 

 subcircular, with the beaks placed a trifle closer to the posterior side, in- 



