686 A. F. FOERSTE 



fied by Schuchert as Spirifer murchisoni, a lower variety of Spiri- 

 fer arrectiis. They are evidently foreign to the Linden bed, and 

 require the identification of the gritty limestone as part of the 

 Camden chert series. 



At Perryville, two silicified specimxcns of Eatotiia peculiaris, and 

 a single specimen of a large form of Camarotoechia (40'"'" long, 

 36'"°^ wide, and 28™"° thick) belonging to the group of 

 Camarotoechia pleiopleura, were obtained loose at the base of the 

 sand and gravel overlying the Linden bed at the quarry. If the 

 identification of the Hardin sandstone in the northwestern corner 

 of Perryville is correct, the Camden chert bed can not exceed 2 

 or 3 feet at this locality, and it is probably altogether absent. It 

 probably occurs, however, a short distance farther north. It is 

 said, by Professor Safford, to occur in Decatur county, but it has 

 not yet been recognized farther southward, in any part of Hardin 

 county. The typical exposures occur at Camden, where the 

 section is at least 60 feet thick. Five miles south of Big Sandy 

 station, on the lower Camden road, the base of the Camden chert 

 is said by Professor Safford to rest upon the Lower Helderberg. 

 The writer has not seen any locality where it is possible to draw 

 any sharp line between these formations. Lithologically, the 

 formations are alike, and paleontologically, the change from the 

 Linden bed fauna to the Camden chert fauna appears to be gradual 

 rather than abrupt. 



The chert derived from the Camden chert appears on the hill- 

 sides for several miles south of Big Sandy station. At the old 

 Williams mill site, 5 miles above the mouth of Big Sandy station, 

 there is a large exposure of the Camden chert bed. The thickness 

 of the bed must be considerably in excess of 50 feet. 



About 4 miles north of Bakerville, at the Whirl in the Buffalo 

 River, the top of the Camden chert rises nearly 50 feet above the 

 river. The exposure may be reached most conveniently by turning 

 off from the Waverly road at the home of Clinton Burcham, 

 following the lane along the northern edge of the hill for half a 

 mile to the home of Henry McClure, and then crossing the field 

 southeastward to the river bluff. The upper layers contain 

 Eatonia peculiaris^ Amphigeiiia curta, Anoplotheca flabellites, and a 



