315 Costa Rica Miocene — Olsson 143 



Uscari Stage: Sapote, C. R. {Gabb) 

 Gatun Stage: Banana River. 



Zone E, Sariry Creek. 



Zoni 5, East Grape Point Creik. 



Genus CREPITACELLA Guppy 

 Crepitacella limonensis, a. sp. Plate 15, figure 17 



Shell small, melanoid in form, with a large body-whorl and 

 shorter conic spire; nucleus of 2 small, smooth whorls followed 

 by 5 post-nuclear whorls; sutures distinct; the whorls are slight- 

 ly coronated and crossed by oblique and slightly curved riblets 

 which become headed on the coronate edge of the spire-whorls 

 just below the upper sutures; on the last whorl, the ribs do not 

 pass below the middle; the surface is covered with faint spiral 

 threads, most distinct on the base of the body-whorl; aperture 

 elliptical, with a thin, oblique outer lip and a subobsolete anteri- 

 or canal; pillar straight. 



Height 8, diameter 4.5, aperture 4 mm. 



The Costa Rican shell, although possibly not mature, is much 

 smaller than the C. cepula Guppy from the Miocene of Venezuela 

 and Sant^l>omingo of the same number of ribs. It differs also 

 in having but 2 nuclear whorls, while cepula has 3. The corona- 

 tion of the whorls which is such a striking feature of the Domin- 

 ican shell, is very much less and inconcpicuous. The longitud- 

 inal costae are more numerous and produce a fine circle of beads 

 as they cross the small coronate edge of the spire-whorls. 



Gatun Stage: Port Eimon, 



Boras del Toro. 



Genus CERITHiUiVi Adanson 



Cerithium costaricensis, n. sp. Plate 10, figure 28 



Shell with a long, slender spire of about 12 whorls (tip brok- 

 ed); sutures deep but somewhat appressed; the profile of the 



