PANAMIC-PACIFIC PELECYPODA 107 



larger ribs fade-out over the anterior and posterior submargins. Color light- 

 cream or whitish, plain or lightly maculated with brown, the tip of the 

 beak and the adductor scars more darkly colored. Hinge plate long and 

 narrow, the teeth usually in an unbroken series. Inner margin finely 

 furrowed. 



Length 57.7 mm., height 48.2 mm., semidiameter 16.5 mm., Holotype, 

 Coast between Punta Blanca and Puerto Callo, Ecuador. ANSP 218915. 



Distinguished from G. maculata by its more elliptical form and produced 

 posterior side, generally lighter and more uniform coloration and fine 

 sculpture. This species seems related to G. spectralis Nicol of the Caribbean 

 but is much larger. 



Range — Panama to northern Peru. Panama: Guanico, Pearl Islands. 

 Ecuador: Punta Blanca, Punta Carnero near Santa Elena. Peru: Zorritos. 



Genus TUCETONA Iredale, 1931 



Type species by original designation, Pectunculus jlabeUatus Tenison- 

 Woods. 



Surface sculptured with strongly emphasized radial ribs between shal- 

 low or deep interspaces, the ribs simple or divided terminally and crossed 

 by concentric wrinkles or striations. Periostracum thin or wanting. 



Tocetona multicostata (Sowerby) 



Pectunculus multicostata Sowerby, 1833, Proc. Zool. Soc. London, p. 195. — Reeve, 1843, 



Conch. Icon., vol. 1, Pectunculus, pi. S, figs. 2, 6. 

 Glycymeris (Tuceta) multicostata (Sowerby), Hertlein and Strong, 1943, Zoologica, vol. 



28, pt. 2, p. 151. 



Shell of medium size (length 40 mm.), subcircular, a trifle higher than 

 long, convex, solid, the umbones wide, oblique, subcarditiform. Ribs between 

 35 to 40, narrow, rectangular, between deep square grooves of nearly the 

 same size, uniform through the middle, smaller on the sides, the ribs and 

 interspaces coarsely cross-threaded. Hinge teeth relatively few and large, 

 the cardinal area subamphidectic, the anterior side longest. Color white, 

 maculated with brown, the interior white or with a brown stain over the 

 posterior portion. 



Range — Coast of Mexico to Ecuador. Ecuador: Isla la Plata, Manta. 

 Colombia: Gorgona Island. Panama: Pearl Islands, Bahia Honda (Hertlein 

 and Strong). 



Tucetona strigilata (Sowerby) Plate 11, figure 3 



Pectunculus strigilatus Sowerby, 1833, Proc. Zool. Soc. London for 1832, p. 196. "Hab. 



ad Sanctam Elenam". — Reeve, 1843, Conch. Icon., vol. 1, Pectunculus, pi. 6, 



fig. 31. 

 Glycymeris (Tuceta) tessellata strigilata (Sowerby), Hertlein and Strong, 1943, 



Zoologica, vol. 28, pt. 3, pp. 152, 153. 

 Glycymeris tessellata strigilata (Sowerby), Hertlein and Strong, 1955, Bull. Amcr. 



Mus. Nat. Hist., vol. 107, art. 2, p. 175, pi. 3, figs. 25-28. 

 Pectunculus tessellatus Sowerby, 1833, Proc. Zool. Soc. London for 1832, p. 196 "Monte 



Christe and in the Bay of Xipixapi". 



