MICROSCOPIC ORGANISMS OF UPPER CRETACEOUS. 



By C. E. McCLUNG. 



Among the numerous organic remains occurring in the Upper 

 Cretaceous of Kansas, the microscopic organisms are not the 

 least interesting and important. In the study of the minute 

 forms of life here found, an interesting field for investigation 

 presents itself, concerning which the present paper gives ac- 

 count of merely a brief incursion therein. This would have 

 been more complete were it not that the material for study was 

 only such as had been collected for other purposes, and so the 

 opportunity was lacking. However, representative samples 

 from- six of the thirteen beds were obtained and carefully 

 studied. Of these, five have rewarded the writer with evidences 

 of their organic origin. Those represented were the Lisbon 

 shale, Hesperornis, Rudistes, Fort Hays, Inoceramus and Lin- 

 coln marble beds. All of these except the first mentioned 

 exhibited well-preserved fossil remains, and this, perhaps, 

 might have done so had more of the material been at hand for 

 study. 



Particular interest centers around the beds of the Niobrara 

 group, for here we find the Kansas chalk which has been more 

 thoroughly investigated and has been more discussed than any 

 of the other deposits. 



English chalk, as is known, is composed almost wholly of 

 foraminiferal remains, imbedded in a matrix consisting of in- 

 organic particles, and the curious discs and rods known as 

 Coccoliths and Rhabdoliths. From the method of chalk forma- 

 tion, it would naturally be supposed that all similar Cretaceous 

 rocks would have a like structure, but for a long time it was 

 denied that there is any true chalk in America, such a state- 

 ment being found in the text-books of Leconte and Winchel] . 

 It was not until 1875 that proof was forthcoming necessary to 



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