2o6 BUI.LETIN 39 378 



Gatun Stage: Gatun, C. Z. 

 Hotel Creek. 



Zone 6, Old Man Sam Creek. 

 Coll. /, East Grape Point Creek. 



Amusium bocasensis, n. sp. Plate 17, figures 3, 4 



Shell rather small, thin and subcircular in outline; moderate- 

 ly Gonvex; ears proportionately larger than in A. luna, and with 

 their dorsal margins slightly inclined upwards from the beaks to 

 their outer edges; the surface is smooth and polished, finely 

 covered with concentric growth-lines and faintly showing the 

 position of the internal lirae; interior of shell with about 34 

 lirae, which are usually nearly evenly spaced and not in pairs; 

 the internal lirae commence well in the interior of the shell, but 

 are strongest distally. 



Height 40, breadth 43. 



35 38, thickness 6 mm. (right valve) 



A much smaller and more delicate species than the Amusiuvi 

 luna Brown and Pilsbry. The internal lirae are more or less 

 equally spaced and not in pairs. It differs from Amusium Lyonii 

 Gabb from the lower Miocene of Sapota, Costa Rica by its much 

 smaller ears. 



Gatun Stage: Bocas del Toro. 



Genus SPONDYLUS, Linnaeus 

 Spondylus chiriquiensis, n. sp. Plate 20, figures r, 2, 5, 6 



Shell large, ponderous, equivalve and strongly convex; both 

 valves of the same convexitj^ but with the beak of the right, 

 high and projecting above the strongly incurved beak of the left; 

 in large shells both valves are provided with a cardinal area, 

 that of the right being both high and wide and for the greater 

 part straight but the beak curving over it to a small extent at 

 its upper end; the cardinal area of the left vale is much smaller, 



