PANAMIC-PACIFIC PELECYPODA 203 



Length 10.9 mm., height 10.8 mm., diameter 2.5 mm. (a right valve, 

 El Lagartillo). 



Small specimens may be subtrigonal in shape with narrow, convex 

 umbones producing the effect of a hunch-backed shell. The largest shell 

 seen, a specimen from the beach at El Lagartillo near Las Tablas, is slightly- 

 less than 11 millimeters long. 



Range — Lower California to Ecuador. Panama: El Lagartillo, near Las 

 Tablas; Bucaro. Ecuador: Puerto Callo. 



J.'iplodoiita (FelanitUa) tellinoliies (Reeve) Plate 32, figures 4, 4a 



Lucina tellinoides Reeve, 1850, Conch. Icon., vol. 6, Lucina, pi. 9, fig. 56 Isle of Muerte, 



Bay of Guayaquil (11 fathoms). 

 Diplodonta (Felaniella) sericata (Reeve), Pilsbry and Lowe, 1932, Proc. Acad. Nat. Sci. 



Philadelphia, vo!. 84, p. 137 listed. 

 Taras {Felaniella) sericatus (Reeve), Hertlein and Strong, 1947, Zoologica, vol. 31, 



pt. 4, pp. 131, 132, pi. 1, fig. 10. 



Shell orbicular to subcircular, the beaks placed a little in front of the 

 middle, thin, depressed to slightly convex, white, covered with a thin, light- 

 brown or horn-colored periostracum. Surface marked with irregular, coarse 

 concentrics showing a slight banded arrangement or undulations suggesting 

 growth intervals. Radial striation if any, is weak. Ligament externa! but 

 deeply inset and crowded against the thin, posterior cardinal tooth. 



Length 20.7 mm., height 18.8 mm., semidiameter 4.7 mm. Tumaco, 

 Colombia. 



Length 23.9 mm., height 22 mm., semidiameter 6.4 mm. Santa Elena, 

 Ecuador. 



This is a common and widely distributed species found mostly on mud 

 flats. The surface is white, covered by a thin, shiny periostracum of a light 

 brown color. 



This shell has usually been identifed by authors with D. sericata Reeve 

 {D. cornea Reeve) but a good series of specimens in my collection from 

 Tumbez, agree best with Reeve's figure of L. tellinoides described from 

 the nearby Isla la Muerte in the Bay of Guayaquil. Dall^'*, however, con- 

 sidered L. tellinoides a Pseudomiltha and compared it with Conrad's Lucina 

 jloridana, a relationship which is questionable. 



Range — Lower California to northern Peru, San Salvador: Gulf of 

 Fonseca (Pilsbry and Lowe, ANSP 178651). Costa Rica: Salinas Bay. 

 ANSP 67147. Panama: Rey and Viveros Islands in the Pearl Island group; 

 Bucaro. Colombia: Tumaco. Ecuador: Charapota; Santa Elena. Peru: 

 Tumbez. 



Diplodonta (Felaniella) cornea (Reeve) Plate 32, figures 1-lb 



Lucina cornea Reeve, 1850, Conch. Icon., vol. 6, Lucina, pi. 9, fig. 25 Nicoiya. 

 Lucina nitens Reeve, 1850, op. cit., pi. 9 fig. 50 Isle of Muerte, Bay of Guayaquil. 

 Lucina sericata Reeve, 1850, op. cit., pi. 9, fig. 55. Hab. unknown. 

 Diplodonta {Felaniella) artetnides Dall, 1909, Proc. U.S. Nat. Museum, vol. 37, No. 1704, 



pp. 156, 263, pi. 28, fig. 8 Capon, Ecuador. 

 Diplodonta {Felaniella) cornea (Reeve), Hertkin and Strong, 1955, Bull. Am. Mus. 



Nat. Hist., vol. 107, art. 2, pp. 184, 185. 



" Dall, W. H., 1909, Proc. U.S. Nat. Museum, vol. 23, No. 1237, p. 812. 



