PANAMIC-PACIFIC PELECYPODA 309 



the ventral margin. Foundation color of the shell is usually a creamy white 

 overrun with a pattern of zigzag brown lines, or the entire surface may be 

 colored a violaceous brown, the lunule and escutcheon a deeper brown. 

 The interior is white with a flush of violet along the posterior end and over 

 the adductor scars; also often under the posterior-dorsal surface. The pallial 

 sinus is small but distinct. Ventral margins finely crenulated. 



Length 19.3 mm., height 16.3 mm., diameter 10.6 mm. Zorritos, Peru. 

 Holotype, ANSP 218962. 



Length 25 mm., height 20.3 mm., semidiameter 12.2 mm. Zorritos, Peru. 

 Paratype. 



This species is common at Zorritos and will be recognized easily by 

 its shape and color; there are generally two color forms, one plain, the 

 other with zigzag markings. Specimens taken at Paita are usually larger 

 and less strongly marked. 



Range — Peru. Peru: Zorritos; Mancora; Paita. 



Nioche (Nioche) mcgintyi, new species Plate 52, figures 2, 2a 



The shell is small or of medium size, rotund, cordate, convex, can- 

 cellately sculptured, marked with angular or zigzag brown lines over a 

 cream-colored foundation. The lunule is large and broadly cordate, flat, 

 neatly sculptured with radial riblets and outlined by an incised line. The 

 escutcheon is a smooth, flat area, bordered by an angle, and confined 

 largely to the left valve. Surface sculpture is produced by small, flat 

 riblets and low, concentric lamellae; on the umbones, the riblets are simple; 

 they are larger on the disk below and near the ventral margin they are 

 grooved or divided into three or more sections, the dividing lines so deep 

 that each primary riblet appears to be composed of parallel cords or broken 

 up into three to five smaller riblets, all of uniform size. The ventral margin 

 is finely crenulated. Interior white with a blotch of purple over the pos- 

 terior section. PaUial sinus short but distinct. 



Length 31.4 mm., height 27.1 mm., diameter 20.5 mm. Palo Seco, 

 Panama Canal Zone. Holotype, ANSP 218897. 



Differs from the somewhat similar N. metodon by its less rounded 

 form, more pointed posterior end, less convexity, and in details of sculpture. 

 The species is named for Mr. Thomas L. McGinty who accompanied the 

 author to Ecuador and Panama in 1953. 



Range — Panama. Panama Canal Zone: Palo Seco. 



Jfioche (Nioche) squamosa (Carpenter) Plate 49, figure 10 



Tapes squamosa Carpenter, 1857, Cat. Mazatlan Shells, Brit. Mus., p. 78, No. 111. 



Chione picta Dall in Willett, 1944, Bull. South California Acad. Sci., vol. 43, pt. 1, p. 

 21, pi. 8, figs. A, B Magdalena Bay, Lower California. — Woodring, 1946, 

 Prof. Paper, U. 8. Geol. Survey, No. 207, pp. 84, 88, pi. 37, figs. 3, 4 Pleis- 

 tocene, San Pedro, California. 



Chione (Nioche) picta (Dall in Willett), Hertlein and Strong, 1948, Zoologica, vol. 

 33, pt. 4, No. 13, pp. 187, 188. 



The shell is always small, usually between six and nine millimeters, 

 ovately oblong, the posterior side much the longer and crudely rounded or 

 squared-off at the end, the surface of the disk depressed to slightly convex. 

 The umbones are wide and inconspicuous, ending in small, adjacent, 

 prosogyrate beaks. The left valve has a small, narrow, flat escutcheon 



