J30 AXEL A. OLSSON 



is a large subspecies found in the upper Miocene beds of northern Peru 

 and the Pliocene of Ecuador. 



Range — Gulf of California to northern Peru. Panama: Old Panama; 

 Bucaro. Panama Canal Zone: Venado Beach. Colombia: Isla del Gallo. 

 Ecuador: Esmeraldas; Sua; Mompiche; Manta; Santa Elena. Peru: Tumbez, 

 Zorritos; Boca Pan. 



Harrella gonloeyma Pilsbry and Lowe 



Mactra {Mactrinula) goniocyma Pilsbry and Lowe, 1932, Proc. Acad. Nat. Sci. Phila- 

 delphia, vol. 8+, p. 90, pi. 15, figs. 5, 6.— Maxwell Smith, 1944, Panaraic Marine 

 Shells, p. 66, fig. 856. 



Mactrella {Mactrinula) goniocyma (Pilsbry and Lowe), Hertlein and Strong, 1950, 

 Zoologica, vol. 35, pt. 4, pp. 234, 235. 



Mactrellona {Mactrinula) goniocyma (Pilsbry and Lowe), Hertlein and Strong, 1955, 

 Bull. Amer. Mus. Nat. Hist., vol. 107, art. 2, p. 205. 



The shell is thin and fragile, translucent whitish, ovate-triangular, 

 the small beaks about median, the anterior end broadly rounded, posterior 

 end triangular. Form rather compressed, a narrow, lanceolate, smoothish 

 posterior area defined by a lamina radiating to the posterior-basal angle, 

 a low convexity between lamina and post-dorsal edge. Sculpture of regular 

 obliquely concentric corrugations which are angulated along a vertical line 

 from the beaks, in form of very broad Vs. The very fine, sharp concentric 

 striation crosses the corrugations obliquely. The lunular region is smooth, 

 lanceolate. Length 16 mm., height 12 mm., diameter 6 mm. (Pilsbry and 

 Lowe, 1932.) 



A rare, poorly understood species. 



Range — Mexico to West Colombia. Mexico: Acapulco (Hertlein and 

 Strong). El Salvador: La Libertad (Hertlein and Strong). Nicaragua: San 

 Juan del Sur. Panama: Pinas Bay (Hertlein and Strong). Colombia: Ardita 

 Bay (Hertlein and Strong). 



Genus BrULDflA Gray, 1837 

 Type species by subsequent designation, Hermannsen, 1847, Mvlinia 

 lateralis (Say). 



Shell small or large, usually heavy. Left valve with strong lateral teeth, 

 equidistant from the cardinals and fitting into deep sockets in the opposite 

 valve. Ligament wholly internal, the resilium seated in a deep chondro- 

 phoral pit, the tensilium attached to a smaller scar in the roof of the 

 chondrophore. The cardinal teeth are fused to form an inverted V, placed 

 directly below the tip of the beak. Pallial sinus short but distinct. Posterior- 

 dorsal areas are generally defined by an angled ridge. Surface smooth or 

 roughened by the lines of growth, and in life covered with a thin, straw- 

 colored periostracum. 



Mulinla pallida (Broderip and Sowerby) Plate 58, figures 2-2c 



Mactra pallida Broderip and Sowerby, 1829, Zool. Journ., vol. 4, No. IS, p. 360 "From 



St. Bias". 

 Mulinia donaciformis Gray, 1837, Mag. Nat. Hist., n. ser., vol. 1, p. 376. — Sowerby, 



1839. Zool. Beechey's Voyage, Moll., p. 154, pi. 44, fig. 13. 

 Mactra donaciformis (Gray), Reeve, 1854, Conch. Icon., vol. 8, Mactra, pi. 13, fig. 60. 

 Mactra angulata Reeve, 1854, op. cit., pi. 9, fig. 34 "Gulf of California". 

 Mactra carinulata Reeve, 1854, op. cit., pi. 10, fig. 38 "Gulf of California". 

 Mactra goniata Deshayes, 1855, Proc. Zool. Soc. London, p. 70 "Gulf of California". 



