22 



Bulletin 4 



136 



From Porter's creek Mr. Johnson obtained fragmentary speci- 

 mens of what appear to be Ostrea cremilimarginata. He says on 

 a slip of paper accompanying the specimens, ' ' Extending from 

 Middleton, Tenn., several miles westward lies the Porter's creek 

 formation of Safford." Hence we are led to believe that the 

 greater part of Safford 's Porter's creek group belongs to the 

 Midway. 



The typical Crainesville-Middleton beds and fauna were found 

 b}^ Johnson at a locality designated as McDonald's mill, 4 miles 

 southwest of Middleton. The various species he collected will be 

 referred to in their proper places under Part II. 



Mississippi. 



Walnut mid vicinity. — In crossing the Mississippi line going 

 south from Middleton one finds the peculiar calcareous gray, 

 green specked, hardened clays of the Crainesville horizon outcrop- 

 ping on the place described by Hilgard in his Agriculture and 

 Geology of Mississippi, p. 112, as the Reeve place. This is 

 about 2% miles northwest of Walnut. Mr. Hubbard made a 



Fig. 2. — Chalybeia'TK Spring, Tippah Co., Miss. 



