366 AXEL A. OLSSON 



Semele Tcrrncosa Morch Plate 65, figures 1-lb 



Semele (Amphidesma) verrucosa Morch, 1860, Malak. Blatter, bd. 7, p. 190 Los 



Bocorones Islands, Costa Rica. 

 Semele verrucosa Morch, Hertlein and Strong, 1949, Zoologica, vol. 34, pt. 4, p. 249, 



pi. 1, figs. 21, 24. 



Shell of medium size (average length 35 to 45 mm.), broadly ovate, 

 the two ends almost equally rounded, inequilateral, the beaks flattened, high, 

 and placed on the posterior side of the middle, the general base color white 

 radially blotched with purple, most heavily near the ventral margin. 

 Sculpture is formed by coarse, concentric riblets which on the anterior and 

 posterior ends become irregularly wrinkled, often splitting up into small 

 segments which resemble a series of small, scalelike nodes, all finely wrinkled 

 on their ventral sides. Interior glossy, white, mottled with purple, the 

 cavity itself often stained yellow. 



Length 54.8 mm., height 42.7 mm., diameter 20.6 mm. Pearl Islands 

 (Mr. Lee R. Beil collection). 



A rare species. Similar in shape and color to S. formosa but the valves 

 are less convex, the concentric riblets coarser and at the ends curiously 

 scalloped or frilled. 



Range — Gulf of California to Panama. Mexico: Gulf of California. 

 Costa Rica; Bocorones Islands (Morch). Panama: Hannibal Banks (Hert- 

 lein and Strong); Pearl Islands (Lee R. Beil coll.). 



Semele rosea (Sowerby) Plate 64, figure 8 



Amphidesma roscum Sowerby, 1833, Proc. Zool. Soc. London for 1832, p. 199 Tumbez. 



—Sowerby, 1833, Conch. Illust., pi. 17, fig. 1.— Reeve, 1853, Conch. Icon., vol. 



8, Amphidesma, pi. 3, fig. 17. 

 Semele junonia Verrill, 1870, Amer. Jour. Sci., ser. 2, vol. 69, No. 146, p. 217 near La 



Paz.— Lamy, 1914, Jour. de. Conchy., vol. 61, No. 3, pp. 356, 357 as a var. of 



roj^-fl.— Hertlein and Strong, 1949, Zoologica, vol. 34, pt. 4, p. 245. 

 Semele tabogensis Pilsbry and Lowe, 1832, Proc. Acad. Nat. Sci. Philadelphia, vol. 84, 



pp. 91, 92, pi. 12, figs. 5, 5a, 5b (Taboga Island, amongst rocks). — Maxwell 



Smith, 1944, Panamic Marine Shells, p. 63, fig. 800. 



The shell is relatively large, thin, broadly ovate in shape, compressed 

 to moderately convex, slightly inequilateral, the beaks nearly central, the 

 posterior submargin weakly flexed forming an impressed area with more 

 subdued sculpture. The anterior side is somewhat longer, broadly rounded, 

 the posterior shorter, straight, subtruncated at the end. The sculpture is 

 formed by regular, concentric, thin-edged, recurved, lamellar riblets, separ- 

 ated by wider interspaces with fine, weak, radial striations. Color is a light, 

 rose-pink shading into apricot or yellow, the beaks always much darker, 

 the interior with the same shade of color. In life, the surface is covered 

 with a thin, light-brown periostracum. 



Length 6U.2 mm., height 51.5 mm., semidiameter 10 mm. (Bucaro, 



Panama). /, , , s o. 



Length 63.7 mm., height 54.2 mm., diameter (both valves) 24 mm. 

 Venado Beach, Panama Canal Zone. 



Semele rosea tabogensis Pilsbry and Lowe Plate 64, figure 7 



The shell is somewhat more obliquely subovate in shape than the 

 typical form, its posterior side longer, the posterior-dorsal margin straighter, 

 more descending and the surface coloration more uniform. 



S. rosea and its subspecies tabogensis are lovely shells distinguished 



