PANAMIC-PACIFIC PELECYPODA 67 



Subgenus COSTELLOLEDA Hertlein and Strong 

 Type species by original designation, Nucula costeUata Sowerby. 

 Shell elongate with strong concentric sculpture. 



Nuculana (Costelloleda) costellata (Sowerby) Plate 3, figure 8 



Nucula costellata Sowerby, 1833, Proc. Zool. Soc. London for 1832, p. 198 (Hab. ad 



Panamam). — Sowerby, 1833, Conch., Illust., Nuculae, p. 4, pi. 15, fig. 8. — ^Reeve, 



1841, Conch. Icon., vol. 1, Nucula, pi. 85, fig. 8. 

 Leda costellata Hanley, in Sowerby, 1860, Thes. Conch., vol. 3 Nuculidae, p. HI, sp. 



11, pi. 228, fig. 59. 

 Nuculana (Costelloleda) costellata (Sowerby), Hertlein and Strong, 1940, Zoologica, 



vol. 25, pt. 4, pp. 398, 399, pi. 2, fig. 10. 



Shell elongate, rather thin, compressed, white, under a pale olivaceous 

 or ash-colored epidermis, occasionally iridescent, the surface sculptured 

 with distant, erect concentrics which terminate just below the posterior- 

 umbonal angle formed by two nodose or squamose ridges enclosing between 

 them a flat, smooth area; interval between the concentric lamellae smooth; 

 posterior-dorsal area or rostrum large, smooth, concave, its margins pouting; 

 lunule linear. A more or less subobsolete anterior ray is generally present. 



Length 22 mm., height 8 mm., diameter (both valves) 4.4 mm. — (Hert- 

 lein and Strong). 



Generally rare. 



Range — Lower California to Panama. 



]N^uciiIana (Costelloleda) marella Hertlein and Strong 



Nuculana (Costelloleda) marella Hertlein and Strong, 1940, Zoologica, vol. 25, pt. 4, 

 pp. 399, 400, pi. 2, figs. 12, 13. 



Much like N, costellata (Sowerby) but is larger, more rostrate, and 

 has finer concentric sculpture. 



Rare. 



Range — Gulf of California to Panama. Panama: Gulf of Chiriqui in 

 35 to 40 fathoms. 



Subgenus THESTTLEDA Iredale, 1929 



Type species by original designation, Leda ramsayi E. A. Smith. New 

 South Wales. 



Shell small or of medium size, thin, the anterior side wide, rounded, the 

 posterior side nearly twice the length of the anterior, sharply narrowed, 

 attenuated and squarely truncated at the end. Surface sculptured with 

 strong, concentric rugae which turn sharply upward as they cross the pos- 

 terior or rostral ridge. Two radial ridges form keels along the rostrum. 

 Chondrophore large. 



This subgenus is based on an Australian species, but the following 

 appears to belong to it also. 



Nuculana (Tliestyleda) lumiata (Carpenter) 



Leda hamata Carpenter, 1864, Kept. Brit. Assoc. Adv. Sci. for 1863, pp. 612, 644. Santa 

 Barbara, Calif. — Sowerby, 1871, Conch. Icon., vol. 18, Laeda, sp. 56, pi. 9, fig. 

 56.— Dall, 1902, Proc. U. S. Nat. Museum, vol. 24, p. 558, pi. 40, fig. 9. 



Nuculana hamata (Carpenter), Grant and Gale, 1931, Mem. San. Diego Soc. Nat 

 Hist., vol. 1, p. 125, pi. 1, figs. 14, 15. 



Nuculana (Thestyleda) hamata (Carpenter), Hertlein and Strong, 1940, Zoologica, 

 vol. 25, pt. 4, pi. 2, fig. 14.— Tucker Abbott, 1954, American Seashells, p. 339, 

 fig. 26d.— Palmer, 1958, Mem. Geol. Soc America, No. 76, p. 61, pi. 2, figi. 4-6. 



