INTRODUCTION. IX 



and the writer. Most of the mapping in Cooper and Pettis 

 Counties was accomplished in one week with the assistance of 

 William Rubey. The work there is much less accurate than that 

 in the counties north of the Missouri River. It can scarcely be 

 considered as better than reconnaissance. The Sedalia and Boon- 

 ville topographic sheets were used as bases for these maps. 



South of Pettis County the writer with assistants followed 

 near the contact of the Mississippian with the Ordovician, ex- 

 amining it in many places, nearly to the Arkansas line, but 

 found no evidences of Devonian save near Warsaw, where some 

 specimens of Atrijpa reticularis (Linnaeus) were collected from 

 the mantle rock. 



In the original plan of the work, Mr. D. K. Greger, then an 

 assistant in the University of Missouri, was to write the paleonto- 

 logic part of the report which deals with the Callaway and Snyder 

 Creek, but he took on other work, and, as the writer had agreed 

 with the state geologist, Mr. H. A. Buehler, to finish a report 

 on the Devonian, he was forced to have collections made, and 

 write the report. He feels that Mr. Greger's long experience 

 with the Snyder Creek shale and Callaway limestone and his 

 extensive collections from the formations would have enabled 

 him to write a more complete paleontologic report on these two 

 formations than is here presented. 



The paleontology of the Cooper is not taken up extensively 

 because Mr. Greger has prefaced a paper on the fauna, which has 

 not been published. Though many species from each of the 

 formations are not listed here the significant forms, from the 

 point of view of stratigraphy, are discussed and the description 

 of other forms will not alter the stratigraphic conclusions ad- 

 vanced. 



Acknowledgments. 



The writer is under obligations to Professor R. R. Rowley 

 for loan of specimens from his collection; to Messrs. Stuart 

 Weller, E. 0. Hovey, John M. Clark and A. 0. Thomas for 

 loans of specimens from the museums of which they have charge; 

 to the assistants and advanced students whose names have been 

 mentioned in preceeding paragraphs, and particularly to Mr. 

 D. K. Greger; to Mr. Klein for. his painstaking care in making 

 the drawings; to Dr. M. G. Mehl for various services which 

 required much time; to Dr. E. M. Kindle for examining some 

 doubtful forms; to Dr. J. E. Hyde for studying a species of 



