INSTITUTE OF SCIENCE, PHILADELPHIA. 285 



Oerithium praecursor Heilprin. 

 Cerithium prcscursor Yip., Trans. Wagner Inst. i. p. 114, pi. 16, fig. 5S, 1887. 



Older Miocene of the Orthaulax bed, Ballast Point, Tampa, Florida, 

 Heilprin, Dall and Crosby. 



This species has on each of the later whorls four prominent, flattish pri- 

 maries separated by wider, channelled interspaces, each containing two or 

 three very fine spiral threads. On the anterior primary the suture is wound. 

 The base and canal have four primaries, usually, with intercalary threads. 

 The aperture is narrower than in most of the preceding species, the pillar 

 simple. When perfect the sculpture is pretty sharp. The species seems to 

 be a precursor of such forms as C. glaphyrea var. lithariiim and C. imtscarum. 



Oerithium chipolanum n. s. 

 Plate 22, figure 7. 



Older Miocene of the Chipola beds, N. W. Florida, Burns. 



Shell of the general type of C. thomasicB Sowerby, but small, with three 

 very small, smooth, compact nuclear whorls and eight subsequent rounded 

 whorls; transverse sculpture of numerous small, rounded ribs extending 

 across the whorl, and which are relatively stronger and more irregular, though 

 less numerous, on the early whorls ; the varices are quite irregular, some 

 being strongly marked and others feeble ; spiral sculpture of three or four 

 primary, little-elevated, flattish threads, separated by wider interspaces, in 

 which are two to four fine secondary threads; there are no beads or nodules, 

 but the primaries appear conspicuous where they cross the ribs; similar 

 sculpture extends over the base ; aperture not much expanded, with a 

 moderate callus and subsutural ridge on the body, a short, recurved canal 

 and arched pillar. Lon. of shell lO; max. diam. 4.5 mm. 



This curious little species sometimes has a flattened aspect yikQ3.Ranella, 

 from the tendency of the varices to be confined to one side. It is not closely 

 related to any of the preceding forms. 



Oerithium sp. indet. 



Older Miocene of the Orthaulax bed at Ballast Point, Tampa Bay, Dall. 



Two specimens in too poor condition to describe, but apparently different 

 from any other known from the strata of that locality and region, were found 

 by the writer at the silex-bed at Ballast Point. 



Oerithium. vinctum Whitfield. 

 Plate 22, figure 9. 

 C. vinctutn Whitfield, Am. Journ. of Conch, i. p. 265, pi. 27, fig. 8, 1865. 



Newer Eocene of Vicksburg, Miss., Whitfield; nine miles southeast of 

 Jewett, Leon County, Texas, J. A. Singley in Coll. Aldrich. 



This interesting species has never been figured in the mature state, and, 



