136 



BUI.I.KTIN 39 



308 



The Costa Rican specimens like those of Santo Domingo are 

 extremely variable in their sculpture. The typical moniliferiun 

 of Jamaica carries on the shoulder of the bodj^-whorl one or two 

 rows of large tubercles or granules and Guppj^'s figure shows the 

 spirals below as finely granulated. 



In Costa Rica, the shells may vary from those with nearly 

 smooth spirals, through transitional forms in which only the su- 

 perior bands are granulated, to the extreme in which all the spirals 

 are finely granulated over the whorl shell. A typical specimen 

 will average : 



Length 35, diameter 22 mm. 



Gatun Stage: Middle Creek. 



Rio Betey. 



Zone 5, Red Cliff Creek. 



Genus SCOMSIA Gray 



Sconsia laevigata Sowerby, var. Gabbi, n. var. Plate 12, figure 3 



cf Cassidaria laevigata Sowerby, 1849, Quart. Journ. Geol. Soc. lyon- 

 don, vol. 6, p. 47, pi. ID, fig. 2. 



cf Cassidaria sublaevigata Guppy, 1866, Idem, vol, 22, p. 287, pi. 27, 

 fig- 9- 



Cassidaria laevigata Gabb, 1881, Journ. Acad. Nat. Sci. Pliila., vol. 8, 

 2nd series, p. 356. 



cf Sconsia sublaevigata Bose, 1906, Bol. Inst. Geol. de Mexico, Numero 



22, p. 36, pi. 4, figs. 9, 10. 

 Sconsia laevigata Frown and Pilsbry, 191 1, Proc. Acad. Nat. Sci. Phila. 



vol. 63, p. 356. 



cf Sconsia laevigata Maury, 1917, Bull. Amer. Pal., vol. 5, p. 275, pi. 

 19, fig. 2. 



As Gabb noted years ago, the Sconsias of Costa Rica are not 

 the typcal laevigata of Santo Domingo but appear to approach 

 more closely in their striated whorls, the Jameican sublaevigata 

 of Guppy and the recent striata of Lamarck. 



Typical laevigata, has generally a distinct shoulder to its 



