313 



Costa Rica Miocene— Olsson 



141 



from below, the side and fr6m above is nearly rectangular , but 

 with the anterior extremity more pointed; the shell is high (about 

 y^, that of the length), with nearly flat or slightly convex sides; 

 dorsal surface convex, a deep depression or pit about the posteri- 

 or 1-4 and low, but large tubercles on each side of the posterior 

 sinus; aperture narrow, curved, with the lips coarsely but regu- 

 larly dentate (about 20 on each lip); posterior sinus is long and 

 vertical; anterior sinus small and rounded; basal surface flat. 

 Length 60, basal diameter 39, vertical diameter 30 mm. 

 This is a species but distantly related to the C. Henkeni So- 

 werby, differing by its longer and higher shell, straight sides and 

 smaller dorsal tubercles. The aperture is strongly curved and 

 very deep on the posterior extremity, ending in the long, vertical 

 sinus. 



Gatun Stage: Water Cay, Panama. 



Genus STROMBUS Linn^us 

 Strombus gatunensis Toula Plate 13, figures 5, 6 



Strombus gatunensis Toula, 1909, Jahrb. der K-K Geol. Reichsanstalt 



Wien, vol. 58, p. 673, pi. 25, fig. 7. 

 Strombus gatunensis Brown and Pilsbry, 1911, Proc. Acad. Nat. Sci. 



Phila., vol. 63, p. 355, pi. 26, figs. 3, 5. 



But two species of Strombus are known from the Gatun beds 

 of Panama and Costa Rica, while five species occur in the synch- 

 ronous Miocene strata of Santo Domingo and four in Jamaica. 

 Other species may therefore be expected with further explora- 

 tion work in Costa Rica. 



In vS. gatunensis, the coiling of the whorls follow closely the 

 shoulder angle so that the last whorl appears very large and the 

 spire low but wide. Young shells occasionally have the shoulder 

 armed with few, large tubercles which later become nearly cov- 

 ered by the close coiling and appressed sutures. The last whorl 

 is large, nearly smooth and with a rounded shoulder angle. 



Occasionally traces of the original coloration is preserved 



