368 AXEL A. OLSSON 



Length 58.1 mm., height 49.4 mm., diameter 23.2 mm. Holotype, British 

 Museum (Natural History). 



Length 66.7 mm., height 56 mm., diameter of a single valve 11.5 mm. 



This may be a race or subspecies of S. sowerbyi, most common to the 

 north of Panama, and distinguished by its somewhat rounder form, finer 

 sculpture, and lighter color, often white. 



Range — Gulf of California to Panama. Mexico: Kino Bay. Costa Rica: 

 Port Parker (Hertlein and Strong). Panama: Isla del Rey, Pearl Islands. 

 (Hertlein and Strong). 



Semele pilsbryi, new species Plate 65, figures 6, 6a 



Shell of medium size, obliquely subovate, the beaks high and trigonal 

 in shape, the lunular area deeply excavated, depressed or of medium con- 

 vexity. Sculpture formed by flattened radial riblets of variable width, 

 separated by lined interspaces, the whole surface in addition coarsely 

 granulose (fig. 6a). A flattened escutcheon is present in the left valve. 

 Surface color a dirty, cream white, the interior apricot except for the hinge 

 teeth which are dark coral red. 



Length 45,5 mm., height 42.4 mm., diameter 10 mm of a left valve. 

 Bucaro, Panama. Holotype, ANSP 218959. 



Known only from a left valve but easily distinguished from all other 

 Panamic Semele by its sculpture and coarsely granulose surface. Named in 

 tribute to the late Dr. H. A. Pilsbry of the Academy of Natural Sciences 

 of Philadelphia. 



Range — Panama. Panama: Bucaro. 



Semele pacifica Dall Plate 65, figure 3 



Semele Pacifica Dall, 1915, Proc. Acad. Nat. Sci. Philadelphia, vol. 61, p, 27.— Hertlein 

 and Strong, 1949, Zoologica, vol, 34, pt. 4, No. 19, pp. 245, 246, pi. 1, fig. 11 

 type. Off La Paz, Lower California. 



Shell of medium size (length about 26 mm.), relatively thin, obliquely 

 subovate, depressed, strongly inequilateral, the anterior side longer, obliquely 

 rounded at the end, the shorter, narrower posterior side having a weakly 

 depressed, flexuous dorsal area, subtruncated at the end. Sculpture consists 

 of numerous, rather strong, radial riblets with narrower interspaces de- 

 veloped over the whole disk, finely and sharply noded by the intersection of 

 concentric ridges. The radial riblets are coarser on the ends, scabrously 

 noded on the posterior slope. General color of the surface is a buff or cream, 

 lightly variegated with zigzag lines of purple. 



This is a beautiful species, closely similar to S. bellastriata of eastern 

 United States. In its typical form, the sculpture is finely cancellate over 

 the whole disk. On the umbones, the radials are mainly developed in the 

 concentric interspaces but ventrally cut deeply into the concentrics, their 

 intersections finely beaded. 



Range — Gulf of California to Panama. 



Semele pnlchra (Sowerby) Plate 65, figure 5 



Amphidesma pulchrum Sowerby, 1832, Proc. Zool. See. London, p. 57. (Sinu Caraccensi, 

 Americae Meridionalis. z= Bahia de Cariques). — Sowerby, 1833, Conch. 

 Illust., sp. No. 2, pi. 17, fig. 2. 



