PREFACE. 



Several years ago a systematic investigation of the Carbon- 

 iferous faunas of the Mississippi basin was begun. Fossils from 

 Iowa, Illinois, Missouri and the neighboring states were col- 

 lected, and the work of examination, comparison and revision 

 of certain groups undertaken. A. large number of species 

 were thus passed in review, and considerable progress made 

 toward the monographic consideration of the forms of different 

 genera. Many type specimens from various cabinets and muse- 

 ums were carefully examined, and accurate drawings made of 

 those which had never been illustrated, or which had been 

 poorly figured. Publication of the results of these studies 

 had already commenced when opportunity was offered, through 

 Mr. Arthur Winslow, State Geologist of Missouri, to modify, 

 temporarily, the original plan, by bringing together all the mate- 

 rial relating directly to the State in the form of a review of the 

 Paleontology of Missouri for one of the reports of the Geologi- 

 cal Survey. To the notes already accumulated which pertained 

 directly to the subject, were added the results of special observa- 

 tions made at different times in various parts of the district. 

 This report was practically ready for the press, and drawings 

 prepared, nearly two years ago. Owing to various delays, chief 

 among which was the preparation of other reports, it did not 

 get into the printers' hands. During the two years which 

 elapsed many new facts had been obtained and new material 

 brought to light. In the meanwhile a change in the adminis- 

 tration of the Survey occurred. 



Immediately afterward the report was taken up, new 

 material added, various parts entirely re-written and the entire 

 work thoroughly revised, so that now it presents quite a differ- 

 ent appearance from what it did when transmitted the first 

 time. 



