PANAMIC-PACIFIC PELECYPODA 281 



Venus cumingii d'Orbigny, 1846, Voy. Airier. Merid., vol. S, 3d pt., Mollusques, p, 563. 



(New name for C. modesta Sowerby. Not Venus modesta Dubois, 1831). 

 Transenella sororcula Pilsbry and Lowe, 1932, Proc. Acad. Nat. Sci. Philadelphia, vol. 



3+, p. 102, pi. 9, figs. 12-16 San Juan del Sur, Nicaragua. (As Macrocallista 



sororcula on plate index). 

 Transennella sororcula Pilsbry and Lowe, Hertlein and Strong, 1948, Zoologica, vol. 



33, pt. 4, No. 13, p. 170. 



Shell ovate, convex, small or of medium size (usually between IS to 

 25 mm. in length), solid, porcellaneous, the umbones prominent and placed 

 at about the anterior one-third. The surface is rather deeply but unevenly 

 grooved concentrically forming low, rounded riblets, strong near the ventral 

 margin, subobsolete above, the general surface glossy. Color white or brown, 

 more often variegated with zigzag lines and triangles of brown on a white 

 base. Interior white irregularly stained with violet. 



Length 22.5 mm., height 18.2 mm., diameter 12.8 mm. Bucaro, Panama. 



Range — Gulf of California to Ecuador. Panama: Pearl Islands (several 

 stations); Bucaro. 



Transennella pannosa (Sowerby) Plate 46, figure 3 



Cytherea pannosa Sowerby, 1835, Proc. Zool. Soc. London, p. 47. — Sowerby, 1851, Thes. 



Conch., vol. 2, Cytherea. p. 635, No. 82, pi. 133, figs. 140-142. 

 Macrocallista pannosa (Sowerby), Dall, 1909, Proc. U.S. Nat. Museum, vol. 37, No. 



1704, p. 266. 



Length of an average shell between 28 to 30 mm., ovate, resembling 

 a small Macrocallista, the umbones and beaks near the middle and rounded, 

 subequal ends, moderately convex, subsolid. The surface is smooth and 

 polished but the umbones and beaks are frequently corroded and chalky. 

 Color varies from a fine mahogany brown to a greenish yellow, often with 

 superimposed radial rays and arrow-shaped markings. Palhal sinus short, 

 extending to about the one-third, broadly or obliquely truncated at the 

 end. 



This is a species of the Peruvian faunal province; records further north 

 in Panamic waters are questionable. 



T. puella Carpenter from Lower California and T. galapagana Hertlein 

 and Strong from the Galapagos, were compared with T. pannosa by Hert- 

 lein and Strong but appear to be smaller species. 



Range — Callao, Peru south to Chile. Peru: Paracas. 



Genus TDfCTORA Jukes-Brown, 1914 



(Callizona Jukes-Brown, 1913, preoccupied by Callizona Doubleday, 

 1848, Lepid., and Greeff, 1875.) 



Type species by original designation, {Callizona Jukes-Brown, 1913), 



Cytherea vtdnerata Broderip. 



Shell suborbicular, solid, the surface ridged concentrically and glossy. 

 Hinge similar to that of Pilar, the anterior and posterior teeth joined above 

 to form a single lamina, the middle cardinal tooth below it. Pallial sinus 

 short, narrow, rounded at the end. Ventral margins crenulated. 



