34d 



Bulletin 39 



25o6d 



Bulla pauperaila Sowerby, 1849, Quart. Journ. Geol. Soc. London, 

 voL 6, p. 52. 



Bulla paupercula Gabb, 1873, T?ans. Amer. Phil. Soc, voL 15, p. 

 246. 



Bulla paupercula Guppy, 1874, Geol. Mag. London, p. 437, 

 Bulla paupercula Guppy, 1876, Journ. Geol, Soc. London, vol. 32, p. 

 518. 



Bulla paupercula Dall, 1890, Trans, Wagner Free Inst. Sci., vol. 3, 

 pt. 1, p, 18. 



Bulla striata Dall, 1903, Trans. Wagner Free Inst., Sci., vol. 3, pt. 6, 

 P- 1583- 



Bullaria paupercula Maury, 1917, Bull. Amer. Pal., vol. 5, p. 182, pi. 

 3. fig. 8, 



Bullaria paupercula Maury, 1920, N. Y. Academy of Science, Tertiary 

 Mollusca of Porto Rico., vol, 3, pt. i, p, 75. 



This species is rare in Costa Rica, and all our specimens are 

 from the Lower Gatun rocks of Middle Creek, It is possibh'' 

 identical with the recent Biillaria amygdala Dillwyn, abundant 

 on the beaches along the northern coast of Panama and Costa 

 Rica. 



Gatun Stage: Middle Creek. 



Genus RINGJCULA, Deshayes 

 Ringicula dominlcana Maury 



Ringicula semistriata f Gabb, 1875, Trans, Amer, Phil. Soc, vol, 15, 



p. 225. Not R. semistriata d'Orbigny. 

 Ringicula doininicana Maury, 1917, Bull. Amer. Pal., vol. 5, p. 185, 

 pi. 3, fig. II, 



This is the most abundant of the Opisthobranch mollusks in 

 the Miocene beds of Costa Rica. The whorls are in general more 

 strongly sculptured with incised lines than typical dominicana 

 from the Miocene of Santo Domingo, and the spiral lines extent 

 over the greater part of the shell, except for a wide, smooth band 

 about the suture. 



The R. hypograpta Brown and Pilsbry,from Gatun is a larg- 

 er shell with a heavier outer lip and more crowded spiral lines 

 about the base. The Costa Rican shells measure about 1.5 mm 

 or less in height. 



Gatim Stage: Middle Creek. Coll. 5, Red Cliff Creek. 

 Coll. 7, Estrella River. 



