220 AXEL A. OLSSON 



DiyarlceUa ebnrnea (Reeve) Plate 31, figure 2 



Lucina eburnea Reeve, 1850, Conch. Icon., vol. 6, Lucina, pi. 8, fig. 49 Santa Elena. 



Divaricella lucasana Dall and Ochsner, 1928, Proc. California Acad. Sci., sen 4, vol. 

 17, No. 4, p. 122, pi. 2, figs. 17, 21, 24. (Nev? name for D. eburnea thought 

 preoccupied by D. eburnea Deshayes, 1835 {nomen nudum). — Hertlein and 

 Strong, 1946, Zoologica, vol. 31, pt. 3, No. 8, pp. 119, 120. 



Divaricella columbiensis Lamy, 1934, Bull. Mus. Nat. Hist. Nat Paris, sen 2, vol. 6, 

 No. 5, p. 433. (New nanne for D. eburnea Reeve, considered preoccupied). 



Adult shell reaching a length of about 24 mm., relatively heavy, often 

 becomes thickened, coarsely punctate, or chalky internally. Umbones and 

 beaks more nearly medial than in the next species. Lunule small. Sculpture 

 usually coarse, forming sharply acute angles in the bend of the lines of 

 divarication; an underlying fine radial striation or internal radial structure 

 usually visible, often strong. 



Length 19.9 mm., height 18.3 mm., diameter 13 mm. fossil, Pliocene, 

 Punta Blanca, Ecuador. 



Length 24.2 mm., height 23.7 mm., diameter 14.8 mm. Santa Elena, 

 Ecuador. 



Both Dall and Lamy changed Reeve's name of D. eburnea on the 

 assumption that it was preoccupied; however, Hertlein and Strong noted 

 that the Lucina eburnea Andrzejowski, Deshayes, 1835 is a nomen nudum 

 and hence has no nomenclatural standing. 



Range — Gulf of California to northern Peru. Panama: Bucaro. Ecuador: 

 Manta, Santa Elena. Peru: Mancora. 



Divaricella perparvnia Dall Plate 31, figures 1-lb 



Divaricella perfarvula Dall, 1901, Proc. U. S. Nat. Museuno, vol. 23, No. 1237, pp. 815, 



816, 829, pi. 39, fig. 8 Acapulco. 

 Divaricella lucasana perparvula Dall, Maxwell Smith, 1944, Panamic Marine Shells, 



p. 58, fig. 726. 



Shell much like D. eburnea showing the same range in size but usually 

 heavier and more convex. Angle of divarication in the incised lines is 

 rounded, blunt, or obtuse. Lunule although quite small is distinct, deep, 

 often with a widely flaring edge. Nepionic shell large, visible, and sculptured 

 with fine, close-set concentric threads. Hinge strong, the cardinal and 

 lateral teeth large and well developed at all stages. 



Length 21 mm., height 21.7 mm., diameter 7 mm. right valve, Viveros 

 Island, Pearl Island, Panama. 



Dall's name of D. perparvula was proposed for a small shell from 

 Acapulco, only briefly described. The figured specimen has a length of but 

 7 mm. It seems probable that this is but a young shell because other speci- 

 mens of Divaricella from Acapulco, although agreeing with Dall's figure 

 as to sculpture, are much larger. The description given above is based 

 mostly on shells from Isla del Gallo, southwestern Colombia, where it is 

 the dominant species. The line of divarication is sometimes partly smooth 

 or obsolete, and the surface is strongly radially striated. 



Range — Mexico southward to Ecuador. Panama: Viveros Island, Pearl 

 Islands. Colombia: Isla del Gallo. Ecuador: Santa Elena. 



