333 Costa Rica Miocene— Olsson 6i 



nearly total lack of spiral sculpturing. The species is named 

 for Dr. W. H. Dall of the National Museum, the author of the 

 genus A ncistrosyrinx . 



GatiDi Stage: Toro Cay, Water Cay, Panama. 



Genus DRJLUA Gray 

 Drillia venusta, Sowerby Plate 4, figure 9 



Pleiirotoma venusta Sowerbj-, 1849, Quart. Jour. Geol. Soc. London, 

 vol. 6, p. 50, pi. 10, iig. 7. 



Pteurotonia venustuui, Guppy, 1866, Quart. Jour. Geol. Soc. London, 

 vol. 22, p. 289. 



Turris {DTitlia) venusta, Gabb, 1873, Trans. Amer. Phil. Soc, vol. 

 15, p. 208. 



Pletirotoma vemista, Guppy, 1876, Ouart. Jour. C-ieol. Soc. London, vol. 



32, p. 527- 

 Pleurotoma venusta, Guppy and Dall, 1896, Proc. U. S. Nat. Museum, 



voL 19, p. 305. 



Drillia venusta Maury, 1917. Bull. Amer. Pal., vol. 5, p. 216, pi. 8, 

 figs. 13, 14. 



The Drillia venusta and consors of Sowerb\', are the two 

 commonest Pleurotomids in the Gatun beds of Costa Rica. 

 Both are characterized b}^ a neat, regular and reticulate sculp- 

 ture of spirals and axial ribs. In venusta, the anal fa.sciole is 

 narrow, and appears as a deep constricted zone, encircling the 

 upper part of each whorl. The spirals are narrow bands, pro- 

 duced between deep, incised lines and in typical specimens num- 

 ber on the last whorl about 18. The canal is rather long and 

 usually more or less twisted. 



Drillia vemcsta, occurs also in the Miocene of Jamaica, 

 Trinidad and in Santo Domingo. 



GatiLn Stage: Gatun, C. Z. 



Banana River, Port Limon. 



Drillia consors, Sowerby Plate 4, figures 8, 10, 13 



PleurotoHia consors, Sowerby, 1849, Ouart. Jour. Geol. Soc. London, 

 vol. 6, p. 50. 



