86 



BUI.LETIN 39 



Height 34, diameter 26, last whorl 17, aperture 19 mm. 



This is a ver\^ distinctive species, characterized by its thin, 

 delicate shell and fine sculpture. It may be compared with the 

 recent T. biillata Sowerby from the Pacific coast of Central 

 America, which differs in its larger, more expansive body-whorl 

 and coarser sculpture. The single specimen was collected from 

 the lower part of the Gatun formation on Toro Cays, in the east- 

 ern part of the Chiriqui Lagoon. 



It is named for Mr. Fred Plummer of the Royal Dutch Oil 

 Company of Hague, Holland. 



Gatun Stage: Toro Cays. 



Subgenus APHERA H. and A. Adams 



Cancellaria islacolonis IMaury Plate 6, figure 12 



Cancellaria tesscllata Gabb, 1873, Trans. Amer. Phil. Soc. vol. 15, p, 



236. Not of Sov»^erby, 1832. 

 Cancellaria islacolonis Maury, 1917, Bull. Amer. Pal., vol. 5, p. 229. 



pi. lo, figs. 12, a, b. 



The C. islacolonis vv^as selected by Dr. Maury, as the guide 

 fossil for the lower of her Miocene formations, the Cercado. It 

 is a very rare fossil in Costa Rica and we have collected it only 

 along Red Cliff Creek, in the eastern part of the Republic. 

 There it occurs in the upper part of the Uscari and in the lower 

 part of the Gatun. 



It is closly related to the recent West Coast C. tesselata 

 Sowerby. 



Uscari formation: Coll. 6, Red Cliff Creek. 

 Gatun formation; Coll. /, Red Cliff Creek. 



