420 AXEL A. OLSSON 



Genus SOLEN Linne, 1758 

 Type species by subsequent designation, Lamarck, 1799 or by Schu- 

 macher, 1817, Solen vagina Linne. 



Shell long, subcylindrical, approximately straight, with the dorsal and 

 ventral margins parallel. Beaks near the anterior end. Valves subequal, sub- 

 truncated and gaping at both ends, the surface smooth or roughened by 

 lines of growth, covered by a smooth or rough periostracum. Ligament 

 external, attached to an elongated nymph. Hinge with a single, large, pro- 

 jecting cardinal tooth in each valve. Adductor scars subequal, distinct, 

 the posterior one placed a short way within the margin, the two scars 

 connected across by a straight, narrow, ribbon-like pallial line, its sinus 

 small and irregular in shape. 



Solen (Solen) pfelfferi Dunker Plate 63, f gure 6 



Solen pfeifferi Dunker, 1861, Proc. Zool. Soc. London, p. 420. "Hab. Caraccas, West 

 Colombia (H. Cuming). — Sowerby, 1874, Conch. Icon., vol. 19, Solen, pi. 6, 

 fig. 26. — Hertlein and Strong, 1950, Zoologica, vol. 35, pt. 4, p. 226, pi. 1, fig. 2. 



Shell small, length usually less than 50 mm., the ratio of height in the 

 order of 1 to 5, nearly straight, thin and fragile, convex, the two ends are 

 slightly, obliquely truncated. Color white or irregularly flushed with violet. 

 Surface smooth and covered by a thin, olive-brown periostracum. 



Length 45 mm., height 8.5 mm., diameter 6.6 mm. Santa Elena, Ecuador. 



Range — Mexico southward to Ecuador. Panama: Guanico. Panama 

 Canal Zone: Palo Seco. Ecuador: Jaramijo; Santa Elena. 



Subgenus SOLENA Morch, 1853 

 (Hypogella Gray, 1854.) 

 Type species by subsequent designation, Stoliczka, 1871, Solen ohliquus 

 Spengler. (S. ambiguus Lamarck). Caribbean and West Indies. 



Beaks not strictly terminal but placed a short space in from the anterior 

 end. Surface covered with a coarse rude periostracum. 



Solen (Solena) rudis C. B. Adams Plate 63, figures 1, la 



Solen rudis C. B. Adams, 1852, Ann. Lyceum Nat. Hist. New York, vol. 5, pp. 524, 525, 

 548, No. 510 "Panama". — Turner, 1956, Occas. Papers on Mollusks, Mus. 

 Comp. Zool., vol. 2, No. 20, p. 83, pi. 19, figs. 1-2. 



Shell often large (length 140 mm.), the ratio of height to length about 

 1 to 4^, solid, straight or slightly curved, the posterior end sharply trun- 

 cated, the anterior end more obliquely so, its margins heavily thickened. 

 Surface of shell white beneath an olive-brown to light, straw-yellow perio- 

 stracum which may be extended beyond the margins of the valves. Growth 

 Unes are coarse, especially so along the posterior-umbonal slope. 



Doubtfully distinct from the Caribbean S. obliquus Spengler from 

 which it differs only by its somewhat more slender form. 



Range — Costa Rica to Peru. Costa Rica: Burica Peninsula, west shore. 

 Panama: Panama City; Guanico; El Lagartillo. Colombia: Isla del Gallo. 

 Ecuador: Sua; Manta; Santa Elena. 



Genus ENSIS Schumacher, 1817 

 Type species by monotypy, Ensis magnus Schumacher. European 

 waters. 



