298 AXEL A. OLSSON 



II. Posterior-umbonal rib short and developed only along the upper side 

 of the umbone. Concentric riblets fewer in number, the greater part 

 of the surface of the disk smooth. Peru. 



C. broggi 



Chione (Iliocliione) submgrosa (Wood) Plate 51, figures 5, 5a 



Venus subrugosa W. Wood, 1828, Index, Test., Suppl., Venus, p. 5, pi. 2, fig. 6 



Panama.— Sowerby, 1834, Gen. Recent and Fossil Shells, No. 41, pi. 250, fig. 



2; pi. 251, fig. 5.— Sowerby, 1853, Thes. Conch., vol. 2, p. 721, pi. 155, fig. 63.— 



Reeve, 1863, Conch. Icon., vol. 14, Venus, pi. 19, fig. 86. 

 Anomalocardia subrugosa (Sovverbv), Dall, 1909, Proc. U. S. Nat. Museum, vol. 37, 



No. 1704, pp. 158, 269, pi. 26, fig. 3.— Hertlein and Strong, 1948, Zoologica, 



vol. 33, pt. 4, No. 13, pp. 190, 191. 

 Chione {Anomalocardia) subrugosa (Sowerby), Parker, Journ. Paleont., vol. 23, No. 



6, p. 587, pi. 89, fig. 10; pi. 92, fig. 20; pi. 93, fig. 4; pi. 94, fig. 15. 



Shell rather coarse and heavy, ovate to elongate subtrigonal, the pos- 

 terior side somewhat rostrate, narrowly or bluntly rounded at the end. 

 Sculpture heaviest on the umbones and consists of low, rounded, concentric 

 folds, tinely radially striated but with a tendency to fade out across the 

 middle of the disk. The posterior-dorsal fold is strong and quite persistent. 

 Color variable, sometimes white, more often with three or more narrow or 

 wide rays of dark brown on a lighter base, often with a fine mottling of 

 broken lines or dots on a white or light-colored base. In life, the surface 

 is covered by a thin, olive-yellow per^ostracum, which is quickly lost, the 

 surface then becomes smooth and polished. The largest specimens seen 

 have a length of nearly 50 mm. 



An average specimen measures: length 45.5 mm., height 35.1 mm., 

 diameter 24.4 mm. Tumaco, Colombia. 



This species seems to prefer a lagoonal or mud flat habitat, and in 

 many places it is harvested in large numbers for food. Many of the shell 

 heaps or kitchen middens along the coasts of Ecuador are largely made up 

 of the valves of this species. 



Range — Gulf of California to Peru (also Chile according to Dall). 

 Panama: Panama City; Pearl Islands; Garachine; Bucaro; Guanico. Pan- 

 ama Canal Zone: Palo Seco; Venado Beach. Colombia: Isla del Gallo; 

 Tumaco; Gorgona Island. Ecuador: Port Limones; Esmeraldas; Cojimenes; 

 Manta; Santa Elena; Puno Island. Peru: Tumbez; Zorritos; Mancora. 



Chione (Il!ochione) brog-gl (Pilsbry and Olsson) 



Anomalocardia broggi Pilsbry and Olsson, 1943, Nautilus, vol. 56, No. 3, pp. 78, 79, pi. 

 8, fig. 7. 



Shell solid, oblong-subtrigonal, highest in the anterior portion or along 

 a line extending from the beak to the anterior-ventral margin which is also 

 the zone of greatest inflation. Sculpture consists of concentric, riblike folds 

 present on the umbones and on the anterior submargins, generally obsolete 

 or absent elesewhere, in addition to a series of fine, radial threads or striae; 

 on some specimens nearly obsolete. The ground color is white or reddish 

 brown with zigzag brown lines and generally three, brown bands radiate 

 from the beak. Length 46 mm., height 37 mm., diameter of a single valve 

 17 mm. Holotype 1789C9 ANSP). 



Differs from C. subrugosa by its somewhat thinner shell, its smoother, 



