PANAMIC-PACIFIC PELECYPODA 81 



B. cancellaria (Lamarck), 1819 (PI. 6, fig. 5) from the Caribbean and 

 western Atlantic is not closely related to either B. lurida or B. barbata, al- 

 though it was generally identified with the European species by past 

 authors (Dall, Sheldon, Maxwell Smith). The Caribbean shell has lower, 

 more anterior beaks, and the ligament covers only the posterior part of 

 the cardinal area, the short anterior portion remaining bare except for a 

 thin extension of the periostracum over it. 



Range — Coast of Mexico southward to northern Peru. Panama: Rio 

 Ocones beach. Colombia: Isla del Gallo. Ecuador: Peurto Callo; Isia la 

 Plata; Santa Elena. Peru: Zorritos; Caleto Sal. 



Subgenus CUCULLAEABCA Conrad, 1865 



Type species by subsequent designation, Stoliczka, 1871, Byssoarca lima 

 Conrad, 1847=C. cucvlloides Conrad, 1833. Eocene and Oligocene of the 

 Gulf States of United States. 



Shell elongate to obliquely subquadrate, subequivalve but usually dis- 

 torted, white under a copious, heavy periostracum. Basal margin sinuated 

 by a wide, byssal gap. Sculpture is formed by fine to coarse, more or less 

 sharply beaded riblets. Hinge long, straight, the teeth in a continuous series 

 in the young but sometimes interrupted later, the distal members larger 

 and oblique. Cardinal area large, high, elongate and subtrigonal, densely 

 covered by wavy or tent-shaped grooves, and completely covered by the 

 ligament on both sides of the beaks. 



Barbatla (Cucnllaearca) reereana (d'Orbigny) Plate 4, figures 4, 4a, 4b 



Area helblingii Bruguiere, Reeve, 1844, Conch. Icon., vol. 2, Area, pi. 14, fig. 90. (Not 



Area helblingii Bruguiere, 1789). 

 Area reeveana d'Orbigny, 1846, Voy. Amer. Merid., vol. 5, pt. 3, Mollusques, pp. <S35, 



636. (New name for A. helblingii in Reeve.) 

 Area (Barbatia) reeveana d'Orbigny, Hertlein and Strong, 1943, Zoologica, vol. 28, pt. 



3, No. 19, pp. 158, 159.— Hertkin and Strong, 1955, Bull. Amer. Mus. Nat. Hist., 

 vol. 107, art. 2, p. 173. 



Barbatia (Calloarca) reeveana (d'Orbigny), Maury, 1922, Paleont. Amer., vol. 1, No. 



4, pp. 175, 176, pi. 2, fig. 13. 



Barbatia (Cueullaearca) reeveana subsp. reeveana (d'Orbigny), Reinhart, 1943, Special 

 Paper, Geol. Soc. America, No. 47, pp. 33, 34, pi. IS, figs. 1-3. 



Barbatia {Cueullaearca) reeveana (d'Orbigny), Rost, 1955, Allan Hancock Pacific Expedi- 

 tions, vol. 20, No. 2, p. 185, pi. 11, figs. 4, 5, 9 ; text-figs. 82 a-c. 



Shell subrectangular but often irregular and distorted, relatively large 

 (up to 100 mm.), subequivalve, depressed to slightly convex, with low, flat 

 umbones and with the beaks placed centrally above the hinge line. The 

 posterior side is usually somewhat extended, higher, obtusely rounded at 

 the end. The left valve has a large, byssal gap along its anterior-ventral 

 margin; the right valve is unaffected or merely shows a slight insinuation. 

 The sculpture is formed by numerous, small riblets between somewhat 

 wider interspaces and fairly uniform over the whole disk. Color white 

 under a rather copious periostracum, generally worn on the umbones, and 

 consisting of short, flattened brown fronds, resembling that of sea-weed, 

 sometimes united or separated into short fronds with spinelike ends. 



