34^ Bulletin 39 2o6d 



Bulla paupercula vSowerby, 1849, Quart. Journ. Geol. Soc. London, 



voL 6, p. 52. 

 Bulla paupercula Gabb, 1873, Trans. Amer. Phil. Soc, voL 15, p. 



246. 

 Bulla paupercula Gupp}-, 1874, GeoL Mag. London, p. 437. 

 Bulla paupercula Guppy, 1876, Journ. GeoL Soc. London, voL 32, p. 



5i8. 

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



pt. 1, p. i8. 

 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 possibly 

 identical with the recent Bullaria amygdala Dillwyn, abundant 

 on the beaches along the northern coast of Panama and Costa 

 Rica. 



Gatun Stage: Middle Creek. 



Genus RINGICULA, Deshayes 

 Ringicula dominicana Maury 



RingiciUa seniistriata ? Gabb, 1875, Trans. Amer. Phil. Soc, vol. 15, 



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

 Ringicula dotnitiicana Maury, 191 7, Bull. Amer. Pal., vol. 5, p. 185, 

 pL 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 PiIsbry,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. 



Gatun Stage: Middle Creek. Coll. 5, Red Clijf Creek. 

 Coll. 7, Estrella River. 



