70 AXEL A. OLSSON 



— Hanley, 1846, Cat. Bivalve Recent Shells, Suppl. pi. 19, fig. 49. (Not Nucula 



lanceolata Lamarck, 1819.) 

 Leda soiuerbiana d'Orbigny, 1846, Voy. Amer. Merid., vol. 5, p. 544. (New name for 



N. lanceolata Sovjrerby, 1833, not Lamarck, 1819.) 

 Leda soiverbiana d'Orbigny, Hanley, 1860, in Sowerby, Thes. Conch., vol. 3, Nuculidae, 



p. 107, No. 2, pi. 227, fig. 33. 

 Adrana sonverbyana (d'Orbigny), Hertlein and Strong, 1940, Zoologica, vol. 25, pt. 4, 



No. 25, pp. 410, 411. 



Shell elongate, compressed, white or translucent, nearly five times as 

 long as high, the beaks flattened and small, placed a little anterior of the 

 middle. The dorsal margin is straight except for a slight upturn at the 

 extreme posterior end. The ventral margin has a uniform gentle curve except 

 for a small sinuation near the anterior end, and a much milder one at the 

 posterior end. Lunule long and narrow, no rostral area, the escutcheon 

 extremely narrow, long and smooth. Sculpture over most of the surface con- 

 sists of fine, close concentric incised lines forming narrow ribbons, occasion- 

 ally smoothing out on the posterior slope, becoming coarser and wider 

 as they bend backwards along the anterior or lunular margin, and strongly 

 sinuated by the bend in the anterior-ventral margin. There is a smooth ray 

 just below the posterior-dorsal margin. 



Length 60.5 mm , height 12.5 mm., diameter 21 mm. right valve. 



Isla del Gallo, Colombia, 



Certain nomenclatural problems connected with this species have been 

 discussed in some detail by Hertlein and Strong. My shell from Isla del 

 Gallo, Colombia, agrees in shape well with that shown by Sowerby (as 

 lanceolata) in his Conchological Illustrations, plate 14, figure 1. 



Range — Panama to Ecuador. Colombia: Isla del Gallo. Ecuador: 

 Xipixapi (Puerto Callo), (Sowerby), 



Adrana crenifera (Sowerby) Plate 3, figures 4, 4a, 4b 



Nucula crenifera Sov^erby, 1833, Proc. Zool. Soc. London for 1832, p. 197. — Sowerby, 



1833, Conch. Illust, Nuculae, p. 3, No. 4, pi. 14, fig. 3. 

 Leda crenifera (Sowerby) Hanley, 1860 in Sowerby's Thes. Conch., vol. 3, Nuculidae, 



p. 110, sp. 8, pi. 227, figs. 37, 38. 

 Laeda arcuata Sowerby, 1871, Reeve, Conch. Icon., vol. 18, Lacda, pi. 4, fig. 20. 

 Nuculana arcuata (Sowerby) Pilsbry and Olsson, 1935, Nautilus, vol. 48, No. 4, p. 118, 



pi. 6, figs. 2, 3. 

 Adrana crenifera (Sowerby), Hertlein and Strong, 1940, Zoologica, vol. 25, pt. 4, No, 



25, p, 408. 



Shell elongate-lanceolate, dull white, slightly convex, the length about 

 four times the height. Beaks small, not quite in the middle, the posterior 

 side being a little longer than the anterior. The dorsal margin is not straight, 

 sloping down slightly on each side of the beak and with the posterior ex- 

 tremity turned up somewhat. The ventral margin is well rounded except 

 near the posterior end which is drawn out and attenuated. Lunule is as 

 long as the anterior side, narrow, bounded externally by a coarse, rounded 

 rib; the escutcheon is similar, its bounding rib finely crenate. Sculpture 

 consists of fine, sharp, concentric threads, evenly developed over the whole 

 surface. There is a distinct, flattened ray below the posterior-umbonal 

 angle. 



This species is locally plentiful along the coast of Ecuador and Peru. 

 A. arcuata (Sowerby), described without indication of locality, appears 



