30I Costa Rica Miocene— Olsson 129 



Length 15.5, diameter 7.5, spire 8, aperture 8 mm, 

 A species with an A7iadiis-\ike sculpture, the ribs and gen- • 

 erall}^ the spirals being persistent. The bodj^-whorl is flattened 

 or slightl}^ contracted about the middle, but less so than in the 

 following variet}^ A long, tapering and nearly smooth spire as 

 in the preceding ,5. cricamola but much more slender and at- 

 tenuated. 



Gatun Stage: Headzuater of Middle Creeks C. R. 



Strom&ina cfsstaricensis, var. musanica, n. var. Plate 10, figures 26, 27 



Shell ovate, with a long, conic spire of 8 or more whorls; 

 last whorl strongly contracted or indented about the middle; the 

 first 3 whorls or more (apex broken) are smooth or sculpturless; 

 on the follovv^ing 3 whorls, the sculpture is largely of numerous, 

 straight rib-like costse, the spirals being only very faint and in- 

 distinct; on the last whorl the ribs number about 14; spirals 

 about 9 on the penultimate whorl as faint raised threads and on 

 the last whorl may be lacking from the middle or contracted 

 zone; aperture linear-ovate, a thickened outer lip with 3 faint 

 denticles below the upper notch; canal straight. 



Length 15, diameter 6.5, spire 13, aperture 8 mm. 



Probably a distinct species from the preceding and differing 

 in its more evenly tapering and more strongly sculptured spire, 

 and deeply contracted body-whorl. It resembles somewhat the 

 figure of ^. cariagensis Brown and Pilsbry from Colombia, but is 

 smaller and has more numerous ribs. The periphery of 5. car- 

 iagensis is rounded. 



Gatun Stage: Banaria River, C. R. 



East fork of Red Cliff Creek. 



Strombina sincola, n. sp. Plate 10, figures 19, 21 



Shell small, wnth a large, conic spire and a dorso-ventrally 

 flattened body- whorl; whorls about 8, the first 3 belonging to the 

 small, smooth, pointed nucleus; sculpture of the post-nuclear 

 whorls of numerous, straight, strong, longitudinal ribs, which are 



