300 AXEL A. OLSSON 



Sculpture formed by numerous, narrowly or widely spaced, raised con- 

 centric lamellae, tilted backwards, the ventral face and interspaces deeply 

 engraved by fine radial cords. Color is usually a plain cream, sometimes 

 a muddy brown, the lunule and escutcheon usually a deep brown. 



Length 55 mm., height 45 mm., diameter 32 mm. Panama Bay, 

 shrimpers. 



This is a common and widely distributed species. Well-preserved speci- 

 mens have an elaborate sculpture, the concentric riblets adorned with large, 

 fluted, toothlike fringes, the space between the adjoining concentrics marked 

 with fine, radial grooves. 



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

 Bucaro; Pearl Islands; Panama Bay, shrimpers. Ecuador: Sua; Mompiche; 

 Galeras; Manta; Punta Blanca; Santa Elena. Peru: Tumbez; Zorritos; Boca 

 Pan; Mancora. 



t'Wonopsis gnldia (Eroderip and Sowerby) Plate 49, figures 1-la 



Venus gnidia Broderip and Sowerby, 1829, Zool. Jour., vol. 4, No. IS, p. 364.— Sowerby, 

 1853, Thes. Conch., vol. 2, p. 709, pi. 154, fig. 25 Pacific Ocean.— Reeve, 1863, 

 Conch. Icon., vol. 14, Venus, pi. 11, fig. 37 San Bias, Mexico. 



Venus (Chione) gnidia Broderip and Sowerby, Grant and Gale, 1931, Mem. San Diego 

 Soc. Nat. Hist, vol. 1, p. 318, pi. 16, figs. 5a, 5b. 



Chione {Chionopsis) gnidia (Broderip and Sowerby), Hertlein and Strong, 1948, 

 Zoologica, vol. 33, pt. 4, p. 184. 



Chione {Gnidiella) gnidia (Broderip and Sowerby), Parker, 1949, Jour. Paleont, vol. 

 23, No. 6, p. 583, pi. 89, fig. 12; pi. 91, figs. 1, 8, 11. 



Similar to C. amathusia but larger and heavier, the concentric lamellae 

 more widely spaced. The outline of the shell varies considerably, the pos- 

 terior end usually subtruncated, less often pointed. 



Range — Gulf of California. 



Chionopsis jamaniana (Pilsbry and Olsson) 



Chione jamaniana Pilsbry and Olsson, 1941, Proc. Acad. Nat. Sci. Philadelphia, vol. 



93, pp. 63, 64, pi. 17, figs. 1, 2 (Pliocene, Jama, Punta Blanca, Ecuador.) 

 Chione {Chionopsis) gnidia jamaniana Pilsbry and Olsson, Hertlein and Strong, 1955, 



Bull. Amer. Mus. Nat. Hist., vol. 107, art. 2, p. 193, pi. 1, figs. 1, 3. Off Punta 



Pasado, Ecuador. 



This shell may be the southern form of Chione gnidia as classified by 

 Hertlein and Strong. The typical form is fossil in the Pliocene of Ecuador. 

 Well-preserved examples of the fossil are more strongly sculptured than 

 Recent C. gnidia, the concentric ridges are more solid, appressed, and their 

 interspaces tend to become smooth in the older shells. 



Range — Coast of Ecuador. Off Punta Pasado. (Hertlein and Strong). 



(Chionopsis oniatissima (Broderip) Plate 51, figures 3, 3a 



Venus ornatissima Broderip, 1835, Proc. Zool. Soc. London, p. 44 Panama. — Reeve, 



1863, Conch. Icon., vol. 14, Venus, pi. 18, fig. 80. 

 Chione traftoni Pilsbry and Olsson, 1941, Proc. Acad. Nat. Sci. Philadelphia, vol. 93, 



pp. 61, 62, pi. 16, fig. 4; pi. 17, fig. 4 (fossil, Ecuador and Panama). 

 Chione {Chionopsis) traftoni Pilsbry and Olsson, Hertlein and Strong, 1900, Bull. Amer. 



Mus. Nat. Hist, vol. 107, art 2, pp. 193, 194, pi. 1, figs. 2, 4. 



