PANAMIC-PACIFIC PELECYPODA 85 



in the middle, the posterior set longer, the sides of the teeth finely grooved. 

 Cardinal area longer than high, the ligament, vertically grooved, and re- 

 stricted to a triangular area under the beak. Adductor scars large, subequal', 

 bordered on the inner side by a raised edge or flange. Sculpture consists of 

 numerous, fine, threadlike riblets between wider interspaces, generally 

 decussated by concentrics. Surface covered by a hairy or bristly perio- 

 stracum. Valve margin smooth or nearly so. 



Arcopsis solida (Sowerby) Plate 6, figures 3, 3a, 3b 



Byssoarca solida Sowerby, 1833, Proc. Zool. Soc. London, p. 18 "Paytam Peruviae". 

 Area solida (Sowerby), Reeve, 1844, Conch. Icon., vol. 2, Area, pi. 16, fig. 106. 

 Barbatia (Fossularea) solida (Sowerby), Maury, 1922, Paleont. Amer., vol. 1, No. 4, 



pp. 21, 22, pi. 2, figs. 7, 12. 

 Area (Areopsis) solida (Sowerby), Hertlein and Strong, 1943, Zoologica, vol. 28, pt. 



3, p. 158. 

 ArcoPsis solida (Sowerby), Rest, 1955, Allan Hancock Pacific Expeditions, vol. 20, No. 



2, pp. 192, 193, pi. 12, fig. 10. 



Shell small (length to about 20 mm.), white or cream-colored and 

 generally encrusted with marine growth. Sculpture is formed by small, 

 radial threads or riblets, finely or coarsely beaded, the surface often worn 

 smooth. Arcopsis adamsi (E. A. Smith) from the Caribbean is a closely 

 similar species but is generally smaller, thinner, and less convex. 



Range — Lower California to northern Peru, and the Galapagos. Pan- 

 ama: Bucaro; Panama City. Colombia: Isla del Gallo. Ecuador: Esmeraldas; 

 Manta; Puerto Callo; Santa Elena. Peru: Zorritos; Mancora; Lobitos; Paita; 

 Yasila; Chimbote. 



Subfamily ANADARIKAE 



Genus ANADARA Gray, 1847 



Type species by original designation. Area antiqvMa Linn^ (Area 

 scapha Meuschen {^maculosa Reeve). Recent, Red Sea. 



Shell of medium or large size, obliquely subovate to elongate, moder- 

 ately solid. Valves convex between tightly closed margins, subequal in size 

 and sculpture. Umbones wide and prominent, terminating m small, proso- 

 gyrate beaks placed over a rather wide, unsymmetrical cardinal area. 

 Cardinal area smooth or nearly so, covered completely by the ligament. 

 The sculpture is nearly similar in both valves and consists of numerous 

 (about 34), close-set ribs, simple, smooth at first but often dividing and 

 becoming bi- or quadruplicate at the ends. Hinge with the teeth arranged 

 in a continuous series, small and vertical in the middle zone, enlarged and 

 divergent at the ends. 



The above description is based on the type specimen of Area antiquata 

 preserved at the Linnean Society of London, supplemented by a few other 

 shells at the British Museum (Nat. Hist.) believed to represent the same 

 species. As indicated by Hanley, the original of Linne's antiquata is a small, 

 somewhat worn left valve which bears the number 144 corresponding to 

 the numeration in the 10th and 12th edition of the Systema Naturae. An 

 external view shown natural size was illustrated by Hanley, plate 3, figure 

 4. Photographs of the same specimen were also furnished Woodring by the 

 Linnean Society and were reproduced by that author in his Bowden mono- 

 graph. A second, larger, unworn specimen with both valves was also found 



