FLINT RIVER OLTGOCENE FOSSILS—DALL. 511 



sutures deep, not channeled, and the whorls well rounded; spiral 

 sculpture comprising two strong rounded cords with a narrower inter- 

 space at the periphery, with two finer threads behind and one in 

 front of the more prominent pair; base convex with about five sub- 

 equal spiral tln-eads with about equal interspaces; the canal short 

 and patulous, the aperture mostly concealed by matrix, but with the 

 outer Hp sHghtly flaring and a prominent rounded varix behind it. 

 Length of shell, 6; maximum diameter, 2.6 mm. 



Locality.— Stsition 7075, on the east bank of FUnt River, about 

 10| miles below Bainbridge, Decatur County, Georgia, and just 

 above Lambert Island; Cooke and Mansfield, 1914. U. S. Nat. 

 Mus. Cat. No. 166730. 



CERITHIUM SILICIFLUVIUM, new species. 



Plate 87, figs. 4, 5. 



Shell large, solid, acute-conic, of 10 or more moderately convex 

 whorls, earlier whorls sculp tm-ed with 11 or 12 retractively arcuate 

 narrow simple axial ribs extending from suture to suture, with wider 

 interspaces, the periphery of the whorls nearer the anterior suture; 

 the cast of this part of the shell (fig. 4) shows no spu-al sculpture; 

 later whorls show an increasing number of more closely set ribs and 

 a slight constriction appears a short distance in front of the suture, 

 giving the effect of a naiTow ill-defined presutural spiral band, which 

 becomes more distinct on the later whorls; spu-al sculpture also 

 appears, at first as fine striae, later as narrow channels separating 

 subequal flattish spiral cords, of which there are seven or eight on the 

 last whorl of the cast (fig. 5). Length of seven whorls, 45; diameter 

 of the posterior whorl of the seven, 5; of the anterior, 18 mm. 



Locality. — Station 3383, at the base of the bluff at Little Horseshoe 

 bend, just below the mouth of Blue (or Russell) Spring branch, 

 Fhnt River, 4 miles below Bainbridge, Decatur County, Georgia; 

 T. W. Vaughan, 1900. U. S. Nat. Mus. Cat. No. 166731. 



Tliis species has the same type of sculpture as C. lyiascotianum, but 

 the reticulation is less coarse, the shell more slender, the whorls more 

 convex, the presutural band narrower and less conspicuous than in 

 that species. In both the casts do not show either the aperture or 

 the base, but the sculptm-e and form are quite sufficient to discrim- 

 inate the species when more perfect examples are obtained. 



Tins species is also found in the lower bed at station 7150a, on the 

 east bank of Fhnt River, near Bainbridge, just below the wagon 

 bridge, in loose blocks of chert, and at station 7096 on the west bank, 

 7 miles above Bainbridge at Red Bluff, by Vaughan, Cooke, and 

 Mansfield in 1914. It is the only species of Cerite known to be 

 common to both horizons. 



