66 AXEL A. OLSSON 



the external surface except for a smooth space below the rostral keel; these 

 riblets are numerous and regular, scarcely as wide as their intervals. 



Tucker Abbott reported this Nuculana as common along the west coast 

 of the United States where it has generally been identified in the past as N. 

 acuta Conrad, an Atlantic Coast species. 



Range — Alaska to Panama. 



Nuculana excarata (Hinds) 



Nucula excavata Hinds, 1943, Proc. Zool. Soc. London, p. 100 Panama in 30 fm. — Hinds, 



1844, Zool. Voy. Sulphur, Moll., pt. 3, p. 64, pi. 18, fig. 17. 

 Leda excavata (Hinds), Hanley, 1860, Thes. Conch., vol. 3, Nuculidae, pp. 31, 32, sp. 52, 



pi. 229, figs. 104, 105. 

 Nuculana excavata (Hinds), Hertlein and Strong, 1940, Zoologica, vol. 25, pt. 4, p. 404. 



Keen, 1958, Bull. Amer. Paleont., vol. 38, No. 172, p. 239.— Keen, 1958, Sea 



Shells of Tropical West America, p. 20, fig. 19. 



A small, rather oblique, sharply beaked shell, short ovate, plump. 

 The posterior or rostral ridge is large and scabrously noded by the sculp- 

 ture which consists of numerous, sublamellose concentric riblets, regularly 

 disposed over the whole surface except on the dorsal areas. The beak is in 

 the middle, the anterior end rounded, the posterior with a sharp beak, its 

 tip narrow and curved upward. 



This species has not been recorded since its discovery and is known 

 only from its original figures and imperfect description. As Myra Keen has 

 recently noted, the name "excavata" is preoccupied (by Goldfuss, 1837) 

 and will need replacement if and when the types or authentically identified 

 specimens are found. 



Range — Panama. 



Subgenus POLITOLEDA Hertlein and Strong, 1940 

 Type species by original designation, Nucula -polita Sowerby. 



Shell relatively large, elongate subelliptical, the posterior end sharply 

 pointed. Posterior-dorsal area narrow, as long as the posterior side and 

 neatly sculptured with small, parallel incised lines. Surface white, poHshed 

 or glazed, with minute growth lines and sculptured with strong, quite 

 widely spaced incised lines which on the posterior side pass upwards obliquely 

 across the umbonal slope, usually fading out on the surface of the mid-um- 

 bones to appear again more widely spaced on the anterior side. Pallial sinus 

 large, widely rounded and reaching to a line under the beak. 

 Nuculana (Polltoleda) polita (Sowerby) Plate 2, figures 1, la 



Nucula polita Sowerby, 1833, Proc. Zool. Soc. London for 1832, p. 198.— Sowerby, 1833, 



Conch. Illust., Nuculae, p. 4, pi. 15, fig. 11. 

 Leda polita Hanley, in Sowerby, 1860, Thes. Conch., vol. 3, Nuculidae, p. 125, sp. 36, pi. 



228, fig. 68.— Sowerby, 1871, Reeve, Conch. Icon., vol. 18, Laeda pi. 3, fig. 16. 

 Nuculana polita (Sowerby), Maxwell Smith, 1944, Panamic Marine Shells, p. 48, figs. 



622, 626C. , ^ 



Nuculana (Politoleda) polita (Sowerby), Hertlein and Strong, 1940, Zoologica, vol. 25, 



pt 4, pp. 397, 398, pi. 2, fig. 9. 



This species is easily recognized by its large size and characteristic 

 sculpture. It is especially common on the beach at Old Panama. 



Range — Guatemala to Panama. Panama: Old Panama; Panama City; 

 San Carlos. Canal Zone: Palo Seco; Venado Beach. For other records see 

 Hertlein and Strong. 



