PANAMIC-PACIFIC PELECYPODA 243 



Like Basterotia but with the nymphal ridge shorter and bearing a small 

 resihal scar on its lower or inner side. 1 he posterior-umbonal ridge is rounded 

 or merely angled. No surface granulation. 



Basterotia (Basterotella) ecnadoriana, new species Plate 36, figures 8, 8a 



JBasterotia peninsularis (Jordan), Hertlein and Strong, 1947, Zoologica, vol. 31, pt 

 4, p. 137. Probably not Jordan, as Anisodonta, 1936, Contri. Dept. Geol. Stanford 

 Univ., vol. 1, No. 4, p. 147, pi. 18, figs. 11, 12 Magdalena Bay, Lower California 

 "Pleistocene". See also Durham, 1950, Mem. Geol. Soc. America, No. 43, p. 95, 

 pi. 25, figs. 3, 8. 



Shell elongate-quadrate, inequilateral, the beaks placed at the anterior 

 one-fourth, the anterior side short, contracted, the longer posterior side 

 with closely parallel dorsal and ventral margins and rounded end, moderately 

 convex, white. The posterior-umbonal slope is prominently vaulted but not 

 angled or keeled. Sculpture produced by coarsely wrinkled concentrics and 

 much finer lines of growth; no granules. 



Length 12.3 mm., height '/.7 mm., diameter of a left valve 2.3 mm. 

 Manta, Ecuador. Holotype, ANSP 218892. 



Length 15.2 mm., height 9.6 mm., diameter of a left valve 3 mm. Santa 

 Elena, Ecuador. Paratype. 



This is probably the species referred to by Hertlein and Strong as B. 

 peninsulare (Jordan), originally described as a Pleistocene fossil from Lower 

 California; the figure of this species given by Durham is that of a more 

 vaulted shell, with deeply impressed ventral side and a more strongly 

 angled posterior-umbonal slope. My shell agrees better with the figure of 

 B. hertleini Durham {op. cit., pi. 25, figs. 4, 110) from the Pliocene of Cali- 

 fornia, but has a longer form and less convexity. 



Range — Gulf of California.? southward to Ecuador and the Galapagos. 

 Ecuador: Manta; Santa Elena. 



STATUS UNCERTAIN 



Solecardia ? obliqna (Sowerby) 



Scintilla obliqua Sowerby, 1862, Thes. Conch., vol. 3, pt. 21, p. 179, No. 32, pi. 235, fig. 

 35.— Sowerby, 1875, Conch. Icon., vol. 19, Scintilla, pi. 4, fig. 34. Ecuador. 



This species is unknown to me. Its short anterior side suggests an 

 Orobhella. 



Superfamily CAEDIACEA 

 Family CARDIIDAE" 



Shell rounded or ovate, equivalve and generally inequilateral, the um- 

 bones prominent, the beaks approximate and prosocoelous, the posterior 

 side of the valves often differing noticeably in sculpture from the rest of 

 the surface. Hinge generally well developed, cyclodont, the cardinal teeth 

 hook-shaped, curving outward and not seated on a flat plate, usually bord- 

 ered by strong laterals. Ligament external, attached to a short, nymphal 

 plate below and behind the beaks. Surface smooth or sculptured with strong, 

 radial ribs, which may be smooth, noded, spiny or scaly; the ribs in some 

 species produce deep furrows or serrations along the ventral and posterior 

 inner margins of the valve. 



The Cardiums may be divided into five groups or subfamilies of which 

 four have member species in the Panamic-Pacific region, the true Cardiums 

 "Keen, A. Myra, 1951, Minutes 111, Conch. Club. S. California, pp. 6-9. 



