418 AXEL A. OLSSON 



cavity and bearing two small, weak cardinal teeth in each valve, the left 

 posterior and the right anterior cardinal teeth bifid, the ethers small and 

 simple; no laterals but the valve margins may be grooved and overlapping. 

 Ligament external, posterior of the beak, the resilifer small, obliquely 

 wedge-shaped and showing a chalky surface texture. Paliial sinus ample, 

 angled, highest in front of the posterior adductor, joining and becoming 

 confluent with the paliial line near the anterior one-third. Adductor scars 

 subequal, shiny. Surface smooth, often polished, the growth lines small 

 and close, covered by a thin, drab-colored periostracum. 



Ardeamya colnmbiensis (Hanley) Plate 74, figures 5, 5a 



Tellina columbiensls Hanley, 1844, Proc. Zool. Soc. London, p. 71.— Hanley in Sowerby, 

 1846, Thes. Conch., vol. 1, p. 307, No. 166 (as 165), pi. 65, fig. 246. Monte 

 Christi. 



Shell elongate-elliptical, compressed or slightly convex, thin or fragile, 

 •white, smooth, with a length up to about 80 mm., but usually smaller. 

 Anterior side is the longer, high, the small beaks somewhat pointed and 

 projecting, the ventral margin widely rounded, the posterior side shorter, 

 pointed or wedge-shaped at the end, straight or in the right valve some- 

 times slightly flexed. Surface smooth and marked with minute lines of 

 growth, the whole covered with patches of a thin, cream or drab-gray 

 periostracum. 



Length 60 mm., height 34.9 mm., diameter of a right valve 5 mm. 

 Tumbez, Peru. 



Length 68.2 mm., height 39.7 mm., diameter of a right valve, 5 mm. 

 Punta Picos, Peru. 



This is a lovely species, distinguished by its depressed, subelliptical 

 shape and white, shiny valves. Although the beaks are small, they rise 

 sharply above the general outline of the valves. 



Range — Panama to northern Peru. Panama: Lagartillo near Las Tablas; 

 San Carlos. Ecuador: Manta; Mompiche. Peru: Tumbez; Zorritos; Punta 

 Picos. 



Genus CTMATOICA Ball, 1889 



Type species, Tellina undvlata Hanley. Santa Elena, Ecuador. 



Shell small, elongated, Nuculana-Wke, the valves thin, white, with a 

 narrowly produced, flexed posterior side and a longer, rounded anterior side. 

 Hinge delicate bearing small cardinal teeth but no laterals. Paliial sinus deep 

 but not extending to the middle and becoming partly confluent with the 

 paliial line below. Surface sculptured with low, wavelike undulations, trans- 

 mitted through the shell, parallel to the concentric growth lines over most 

 of the disk but cutting across them on the anterior slope. 



Cymatoica ondulata (Hanley) Plate 69, figure 7 



Tellina undulata Hanley, 1844, Proc. Zool. Soc. London, p. 72.— Hanley, 1846, Thes. 



Conch., vol. 1, Tellina, p. 310, pi. 59, figs. 107, 107a Santa Elena. 

 Cymatoica occidentalis Dall, 1900, Proc. U. S. Nat. Museum, vol. 12, No. 773, p. 272, 



pi. 10, fig. 11. 

 Macoma (Cymatoica) undulata (Hanley), Maxwell Smith, 1944, Panamic Marine 



Shells, p. 66, fig. 850F.— Hertlein and Strong, 1949, Zoologica, vol. 34, pt. 2, 



No. 9, p. 89.— Hertlein and Strong, 1955, Bull. Araer. Mus. Nat. Hist, vol. 107, 



art. 2, p. 200. 



Shell small, thin, with strongly flexed valves, white or glassy. Beaks 

 small and erect, placed at the posterior third, the posterior side behind 



