96 AXEL A. OLSSON 



Anadara (Cuiiearca) perlablata (Grant and Gale) Plate 9, figures 2, 2a 



Area labiata Sowerby, 1833, Proc. Zool. Soc. London, p. 21. — Reeve, 1843, Conch, Icon., vol. 



2, Area, pi. 1, fig. 7. Not A. labiata Solander, 1786 "Hab. ad Real Llejos et ad 



Tumbez." 

 Area (Area) perlabiata Grant and Gale, 1931, Mem. San Diego Soc. Nat. Hist., p. 141. 



New name for A. labiata Sowerby. 

 Area (Cunearea) perlabiata Grant and Gale, Hertlein and Strong, 1943, Zoologica, vol. 



28, pt. 2, p. 161. 

 Anadara (Cunearea) perlabiata (Grant and Gale), Reinhart, 1943, Special Paper, 



Geol. Soc. America, No. 47, p. 70, pi. 14, figs. 1, 2, 6. 



Shell small or of medium size (up to about 36 mm.), nearly equivalve 

 (the left valve a trifle larger than the right), subquadrate, the anterior- 

 ventral side convex and rounded, the posterior-ventral margin slightly 

 inflexed because of a weak surface depression extending downward from 

 the beak to the ventral margin. Umbones prominent and nearly central 

 terminating above in small, narrow, pointed beaks curved over a high, 

 triangular, ungrooved, cardinal area. Sculpture discrepant on the two valves, 

 the ribs of the left valve being neatly beaded over the umbone and anterior 

 umbonal slope, later becoming smooth ventrally, the ribs of the right valve 

 being narrower and smooth from the first, only a few of the ribs on the 

 anterior slope below the beak being noded. The ribs number between 26 to 

 28, of which 9 are placed on the posterior slope. Surface white under a 

 thin, black periostracum which scales off easily and on beach shells is pre- 

 served only in patches; when well preserved the periostracum shows cross 

 scales in the intervals on both valves. Hinge line shorter than the length 

 of the shell, the teeth small and in a continuous uninterrupted series. 



Length 33.2 mm., height 33.1 mm., diameter 32 mm. Puerto Pizarro, 

 Tumbez, Peru. 



Length 36 mm., height 36.4 mm., diameter of a left valve 16 mm. 

 Tumaco, Colombia. 



This is a mud-flat species, often found in the mouth of rivers where it 

 occurs with Anadara grandis. Chione (Iliocliione) subrugosa, Dosinia dunkeri 

 and Diplodonta. It is especially common at Tumaco, Colombia, and at 

 Puerto Pizarro in the mouth of the Tumbez River, Peru. 



Range — Lower California to northern Peru. Panama: San Miquel, Pearl 

 Islands. Colombia: Tumaco. Ecuador: Manta; Puerto Palmito, Santa Elena. 

 Peru: Puerto Pizarro, Tumbez River. 



Anadara (Cunearea) nux (Sowerby) Plate 9, figures 8, 8a 



Area nux Sowerby, 1833, Proc. Zool. Soc. London, p. 19 Xipixapi. — Reeve, 1843, Conch. 



Icon., vol. 2, Area, pi. 1, fig. 1. 

 Seapharea (Cunearea) nux (Sowerby), Maury, 1922, Paleont. Amer., vol. 1, No. 4, 



p. 196, pi. 3, figs. 7, 8. 

 Area (Cunearea) nux Sowerby, Hertlein and Strong, 1943, Zoologica, vol. 28, pt. 3, p. 



161.— Hertlein and Strong, 1955, Bull. Amer. Mus. Nat. Hist., vol. 107, art. 2, 



p. 173. 

 Anadara (Cunearea) nux (Sowerby), Rost, 1955, Allan Hancock Pacific Expeditions, 



vol. 20, No. 2, pp. 205, 206, pi. 16, figs. 20 a-c; text-figs. 91 a-c. 



Shell small, cordate, convex, subequivalve, the umbones wide and ter- 

 minating in small, incurved beaks placed at the anterior one-third and 

 separated by a fairly high, cardinal area longer than wide. The sculpture 

 of the two valves is somewhat discrepant, the ribs on the left valve being 



