46g AXEL A. OLSSON 



Subgenus AGRI0DES3IA Dall, 1909 



Type species by original designation, Entodesma saxicola Baird. Van- 

 couver Island. 



Generally large, much distorted shells due to a nestling habit in rock 

 crevices, the surface covered with a coarse, horny periostracum which in 

 drying generally peels off exposing the pearly shell below. The lithodesrna is 

 a large plate, and with the resilium, it is inserted obliquely below the hinge 

 margin and between the two valves. 



Entodesma (Agriodesma) sechurana Pilsbry and Olsson Plate 83, figure 5 



Entodesma {Agriodesma) sechurana Pilsbry and Olsson, 1935, Nautilus, vol. 49, No. 

 1, pp. 18, 19, pi. 1, figs. 6, 7, 8. 



The shell is rather large, irregular in form, pearly within and covered 

 externally with a dark-colored periostracum; the beaks are small and 

 terminal. The anterior end is sometimes slightly produced and convex, but 

 more often, it is flattened and truncated. The posterior side is generally 

 broadly expanded, the ventral and dorsal margins nearly parallel, and in 

 the young, there may be a lunular depression below the beak. The anterior- 

 ventral margin has a wide, elliptical gap, the margins of the shell about the 

 gap often much deformed, sometimes producing furrows which extend up- 

 ward to the beaks. Interior nacreous, the adductor scars conspicuous. 



Length 68 mm., height 41 mm., diameter of left valve 18 mm. Holotype, 

 ANSP 164624. 



This species attains about the same size as the northern E. saxicola. 

 It is a fairly common species in Sechura Bay, probably a migrant from the 

 south. A few small specimens have also been found at Bucaro in Panama. 



Range — Panama southward to Peru. Panama: Bucaro. Peru: Bayovar, 

 Bay of Sechura; Lobitos; Mancora; Punta Picos. 



Entodesma (Agriodesma) picta (Sowerby) Plate 84, figures 7, 7a 



Lyonsia picta Sowerby, 1834, Proc. Zool. Soc. London, p. 88. "Hab. ad Insulam Muerte". 

 Osteodesma picta (Sowerby), 1875, in Reeve, Conch. Icon., vol. 20, Mytilimeria, pi. 



1, fig. 6. 

 Entodesma picta (Sowerby), Dall, 1915, Proc. U.S. Nat. Museum, vol. 49, p. 455. 

 Lyonsia {Entodesma) picta (Sowerby), Lamy, 1928, Jour, de Conchyl., vol. 76, p. 260 



(prob. in part). 

 Lysonia inflata Conrad, 1837, Jour. Acad. Nat. Sci. Philadelphia, vol. 7, p. 248, pi. 19, 



fig. 10 "Guayaquil". 



Shell thin, elongately subovate in shape, convex over the umbonal 

 middle part, depressed over the posterior part. The anterior side is short, 

 somewhat flatly impressed, its margin declining straight or a little rounded, 

 the posterior side narrower, depressed, its dorsal margin straight, sub- 

 truncated and gaping at the end. The surface over the convex portion is 

 narrowly and rather regularly, concentrically undulated except for a line 

 above the anterior-ventral gap where the undulations are wrinkled or sharply 

 bend inward; over the posterior portion, the undulations are weak or missing. 

 Periostracum thin, skinlike and peels off easily revealing a whitish surface 

 underneath. Interior is a pearly white, the muscle and pallial impressions 

 showing faintly. Lithodesma large and prominent. 



Length 23.5 mm., height 15.6 mm., diameter 12 mm. Peru, ANSP 55366. 



