170 AXEL A. OLSSON 



Differs from the Caribbean species commonly identified as Lima lima 

 by its more convex shell, less flattened anterior side, and coarser ribs. Fairly 

 rare. 



Range — Lower California to Ecuador. Ecuador; Atacames. Colombia; 

 Gorgona Island (Hertlein and Strong) For other records see Hertlein and 

 Strong. 



Subgenus SUBMANTELLUM Olsson and Harbison, 1953 



Type species by original designation, Lima orbignyi Lamy. 



Shell obliquely subelliptical, thin, inflated with the valves closed or 

 nearly so on all sides. Sculpture formed by fine, sharp, radial threads spaced 

 irregularly between wider interspaces. 



Lima (Submantellnm) orbigrnyl Lamy Plate 17, figure 3 



Lima angulata Sowerby, 1843, Thes. Conch., vol. 1, p. 86, pi. 22, figs. 39. 40. (Not Lima 



angulata Miinster, 1841. 

 Lima (Mantellum) orbignyi Lamy, 1930, Iovlt. de Conchyl., vol. 74, No. 3, p. ISO. 



(New name for L. angulata Sovyerby, not Miinster). 

 Lima (Limaria) orbignyi Lamy, Hertlein and Strong, 1946, Zoologica, vol. 31, pt. 2, 



pp. 67, 68. 



The largest specimen seen measures about 38 mm. high. The shell is 

 thin and strongly convex. Most of our specimens have a flat margin and a 

 gap, if present, must be small. 



Range — Mexico south to northern Peru and the Galapagos. Panama 

 Canal Zone: Palo Seco. Panama: Bucaro. Colombia: Isla del Gallo. Ecuador: 

 Manta; Santa Elena. Peru: Zorritos; Paita. 



Subgenus PROMANTELLUM Iredale. 1939 

 Type species by original designation, Prom^ntellum parafragilis Iredale, 

 Recent, Great Barrier Reef, Australia. 



Shell thin, with flattened, somewhat flexed, oblique valves, widely 

 gaping on both the anterior and posterior sides, in contact only at the 

 hinge and ventral margin. 



Lima (Promantellum) pacifica d'Orbigny Plate 17, figure 1-lb 



Lima arcuata s'owerby, 1843, Thes. Conch., vol. 1, p. 86, pi. 22, figs. 41, 42. Not Lima 



arcuata Geintz, 1840. Sowerby in Reeve, 1872, Conch. Icon., vol. 18, pi. 4, 



figs. 6, 16. 

 Lima pacifica d'Orbigny, 1846, Vol. Amer. M^rid., vol. 5, p. 654. (New name for 



Lima arcuata Sowerby, not of Geintz). — Maxwell Smith, 1944, Panamic Marine 



Shells, p. 53, fig. 691. 

 Lima (Promantellum) pacifica d'Orbigny, Hertlein and Strong, 1946. Zoologica, vol. 



31, pt. 2, p. 66. 



Shell about 35 mm. in height, white, narrowly elongate, vaulted, the 

 umbones flattened. The hinge and umbonal area are comparatively narrow, 

 the posterior side wider and expanded, the anterior and posterior sides 

 widely gaping. Surface sculptured with 30 or more wavy, slightly scabrous, 

 radial threadlets. 



Range — Mexico to northern Peru and the Galapagos. Panama: Bay 

 of Panama. Ecuador: Charapota; Manta. Peru: Zorritos; Mancora; Lobitos; 

 Negritos. 



