Foerste — Eocene and Miocene of Georgia and Florida. 45 



striction between these ribs, and a slope from the last named 

 rib to the posterior suture. By addition of other spirals both 

 ribs assume later the form of elevated bands defined by two 

 spirals each. By the adding of striae in the groove and on the 

 posterior slope the later formed whorls may become heavily 

 ornamented. The Eocene form of this shell occurs at 5, two 

 miles east of Marianna at the quarry, 4, and six miles north of 

 Bainbridge on the west side of the Flint River, at the grave- 

 yard locality. At locality 5 at the river's edge is silicified 

 rock more evidently in place and resembling that at locality 6. 

 At 6, the silicified layer is well exposed and contains Orbi- 

 toides, sponges, massive and also simple corals, Ostrea, Pecten, 

 a rock-boring lamellibranch, Strombus, and two species of 

 Cerithium. A little farther up the river the soft white lime- 

 stone which once filled in at least a part of the intervals be- 

 tween the various silicified layers, is still visible ; it occupies a 

 slightly lower level and contains Orbitoides. 



{f) At T occurred a silicified bed containing chiefly sponges, 

 but also many massive corals, a concentrically striated Modiola 

 85 mm long, Cytherea, Ampullina, and the^ two species of Ce- 

 rithium above mentioned. The layer bears evidently close 

 faunal and lithological relations to layer e, but this does not 

 necessarily imply the identity of the layers. At 8 a single 

 large bowlder contains chiefly sponges, but also a stray Cytherea, 

 and a large massive coral. 



(</) The next layer is exposed at 9 and 10 and on Lambert's 

 island. It is strongly characterized by being the only rock 

 along the Flint River section here given, which look more like 

 a sandstone than an ordinary silicified layer. At 9 it is more 

 like sandstone and only a few small stray bowlders contained 

 fossils, Pectunculus and Pectens. At 10 the more silicified 

 material is full of Pectunculus and Pecten, and a stray astraei- 

 form coral was seen. At 11 and 16 the soft white limestone, 

 which formed such a large part of the upper Eocene section, 

 but which is usually worn away between the silicified layers 

 along the river banks, is exposed. At 11 it contains Orbi- 

 toides and at 16 are found Orbitoides and a few Pectens. 



(h) The highest silicified layer in the Vicksburg section is 

 that found at 12, 13, 15, and IT. The deviation from parallel- 

 ism between this line and the Chattahoochee outcrops is prob- 

 ably due to the difficulties in platting a river from a skiff. At 

 12 sponges are common and Pectens seem frequent. At 13, 

 many Orbitoides and a sea-urchin occur. At 15, were found 

 many concretionary looking sponges and a few Pectens. At 

 IT were abundant Orbitoides and stray Peccens. 



