90 AXEL A. OLSSON 



Anadara (Dilnrarca) adamsi, new species Plate 6, figures 7, 7a, 7b 



The shell is relatively small (length 23 mm. or less), subrectangular, 

 with wide umbones ending in small, slightly sulcated beaks placed near the 

 anterior one-fourth, this line is also the zone of greatest height and con- 

 vexity; posteriorly the height narrows as the ventral margin advances 

 slightly upward, its posterior-ventral comer being slightly produced and 

 angular. The hinge line is straight, about half the length of the shell and 

 bears a continuous series of small teeth, numbering about 15 in the anterior 

 set and about 20 in the longer posterior set; the teeth are finely striated on 

 the sides. Cardinal area is of medium height, almost wholly covered by the 

 ligament which generally carries a single, transverse groove on the posterior 

 side. The surface is sculptured with small ribs, about 30 in number, and 

 similar over the whole disk; on some specimens, the ribs are strongly noded, 

 especially over the anterior side; in others, the ribs are weakly noded to 

 smooth. The umbones are slightly sulcated. Color white, the periostracum 

 thin and showing generally only as crossthreads in the interspaces of the 

 ribs. 



Length 23 mm., height 16 mm., diameter 14.6 mm. 



Palo Seco, Canal Zone. Mr. Lee R. Beil Coll. 



Holotype, ANSP 218916. 



This is a small species, fairly common at Palo Seco, Canal Zone. The 

 posterior-ventral side is slightly impressed. 



Range — Panama. Panama Canal Zone: Palo Seco. 



Anadara (Dilnvarca) lablosa (Sowerby) Plate 84, figures 10, 10a 



Area labiosa Sowerby, 1833, Proc. Zool. Soc. London, p. 21 Turabez, Peru. — ^Reeve, 1844, 



Conch. Icon, vol. 2, Area, pi. 10, fig. 67. 

 Seapharea (Seapharca) labiosa (Sowerby), Maury, 1922, Paleont. Amer., vol. 1, No. 



4, pp. 192, 193, pi. 31, figs. 1, 3. 

 Anadara (Seapharca) labiosa (Sowerby), Reinhart, 1943, Special Paper, Geol. Soc. 



America, No. 47, p. 74. — Keen, 1958, Sea Shells of the Tropical West America, 



p. 38, fig. 63. 



The shell is broadly rectangular, with wide, low umbones, the valves 

 slightly unequal, that of the left being a trifle larger so that the posterior- 

 ventral margin overlaps and slightly embraces the other. The posterior 

 margin is obliquely truncate, its dorsal corner set at an angle about 120 

 degrees. Ribs numerous, about 39 in number, relatively narrow and flat- 

 topped, the periostracum thin and of a brown color. 



Length 56.4 mm.; height 35.9 mm.; diameter 26.9 mm. Holotype, British 

 Museum (Natural History). 



In the type lot at the British Museum there are three complete speci- 

 mens and one small valve. The above description is based largely on the type 

 material. This is apparently a rare species and has been collected only on a 

 few occasions. 



Range — Lower California to northern Peru. Mexico: Gulf of California 

 and Acapulco. Peru: Tumbez. 



Subgenus RASL4 Gray, 1857 



Type species by subsequent designation, Stewart, 1930, Area formosa 

 Sowerby. (Cara Gray, 1857, type species by subsequent designation, Stewart, 

 1930, Area avieuloides Reeve, 1844 (young of Area formosa Sowerby). 



