PANAMIC-PACIFIC PELECYPODA 197 



569, pi. 83, figs. 14, IS Guayaquil.— Prime, 1865, Smith. Misc. Coll., No. 145, 

 p. 21, No. 16, fig. 16.— Sowerby, 1876, Conch. Icon., vol. 20, Cyrena, pi. 9, fig. 

 34. 



Shell of medium size, ovate-trigonal, slightly convex, the umbones full, 

 erect, slightly anteriorly placed and narrow. The anterior side is short and 

 rounded, the posterior somewhat longer, produced and bluntly pointed at 

 the end. Surface covered with smoothish, raised concentrics and overlain 

 by a brown or green periostracum, generally well preserved on specimens 

 seen. Interior violet. 



Length 51.4 mm., height 42.4 mm., diameter 26.1 mm. Guayaquil. 

 Ecuador. ANSP 54635. 



Similar in general shape to E. triangula but more regular and the 

 sculpture smoother. 



Range — Ecuador. Ecuador: vicinity of Guayaquil. 



Neocyrena trlaiigula (von du Busch), Philippi Plate 27, figures 2, 2a; 



Plate 28, figure 3 



Cyrena triangula von du Busch, Philippi, 1949, Abbild. und Beschrieb. Conchylien, bd. 

 3, p. 78, tab. 2, Cyrena, fig. 3.— Prime, 1865, Smith. Misc. Coll., No. 145, p. 14, 

 No. 5 Mazatlan. 



Cyrena altilis Gould, 1853, Proc. Boston Soc. Nat. Hist, vol. 6, p. 400, pi. 16, fig. 5. 



Cyrena oltvacea Carpenter, 1857, Cat. Mazatlan Shells, Brit. Mus., pp. 114, 115 Mazat- 

 lan,— Prime, 1865, op. cit., pp. 17, 18, No. 10, fig. 12.— Sowerby, 1876, Conch. 

 Icon., vol. 20, Cyrena, pi, 9, fig. 12. 



Neocyrena triangula (von du Busch), Fischer and Crosse, 1894, Miss. Scient. a Mexique 

 «t I'Amerique centrale, septe parte, tome II, p. 78. 



Neocyrena oUvacea (Carpenter), Fischer and Crosse, 1894, op. cit., pp. 634, 635, pi. 

 70, figs. 5, 5a, 5b. 



This species is similar to A^. fontainei but has a more triangular shape 

 and a more irregular and somewhat different surface sculpture. According 

 to Carpenter, it is known outwardly by its flattened form, elevated, trigonal- 

 cordate shell, its posterior end with a short but evident beak, and a surface 

 covered by a rich olive or dark-brown, glossy periostracum. The sculpture 

 is formed by small, rounded concentric costae which are even and strong 

 on the anterior slope, smoother or subobsolete over the middle portion and 

 more irregular on the posterior side. The interior is generally marked with 

 deep purple. The adductor scars are placed close to the margin. There is 

 a small but distinct pallial sinus pressed close to the adductor scar. 



Length 58.2 mm., height 47.8 mm., diameter 28.5 mm. Mazatlan, 

 Mexico. ANSP 54945. 



Range — Mexico. Mexico: Mazatlan. 



JVeocyrena fortls (Prime) Plate 28, figures 2-2d 



Cyrena fortis Prime, 1861, Jour, de Conchyl., vol. 9, p. 355; vol. 10, p. 387, pi. 14, fig. 

 2 South America in Ecuador.— Prime, 1865, Smith. Misc. Coll. No. 145. p. 17, 

 fig. 11. 



Shell rounded, trigonal, solid, depressed or of medium convexity, in- 

 equilateral, the posterior side longer, weakly carinated along the umbonal 

 slope and obliquely subtruncated at the end. Beaks large, prosogyrous but 

 seldom perfect, the umbonal surface being nearly always deeply corroded. 

 The sculpture is formed by small but strong concentric costae, even or 

 regular over the disk proper, generally ending at the posterior-umbonal 



