Belemnitella Americana and Mucronata [312 



hard limestones at wide intervals," and as chalk has been 

 found to be one of the two facies in which B. americana prac- 

 tically always occurs, the various localities need not be consid- 

 ered in detail. In the case of the two Eipley occurrences, 

 however, the lithology must be examined. 



Dr. L. W. Stephenson, of the U. S. Geological Survey, has 

 kindly furnished me with the following information in regard 

 to these occurrences. The locality one-quarter mile east of 

 Troy, Mississippi, came from a "gray, highly calcareous 

 sandstone," of which Dr. Stephenson sent me a sample. The 

 rock bears not the slightest trace of glauconitic material, but 

 is composed to a very large degree of limestone, of a chalky 

 character. In places the sand grains, milky quartz, are 

 embedded in a solid calcareous matrix. Thus, while not per- 

 haps occurring in the Selma Chalk proper, the lithology of 

 the beds may be regarded as identical with that of many 

 parts of the Chalk formation. Of location 544, in Tippah 

 County, Mississippi, Dr. Stephenson says, " the matrix at- 

 tached to one specimen in the lot is gray, calcareous, glau- 

 conitic ( ?) sand." This specimen is a Serpula. He does not 

 go into further detail regarding the locality, but it may be 

 a fair inference, despite a warning that some of this material 

 may be mixed, that glauconite was present at least in the 

 vicinity of this occurrence of B. americana. It is rather 

 significant in this connection to note that the glauconite 

 locality was in the true Ripley, at some distance from the 

 Selma Chalk, and the non-glauconitic, but highly calcareous 

 facies, was very near to the contact of the Selma and Ripley. 



The most noteworthy gap in the range of B. americana in 

 the southeastern United States is in Georgia. Here the 

 Eipley formation is well developed, attaining a maximum 

 thickness of about 850 feet, but nowhere in the large area 

 covered by the formation, which at times is somewhat glau- 

 conitic, is B. americana recorded. The many sections of the 

 Ripley given by Veatch and Stephenson (10), and the nu- 

 merous fossil collections, never mention B. americana. This 

 is probably due to the Georgian Ripley being a nearer-shore 



