viii University Geological Survey of Kansas. 



their work has been done under general directions and advice, 

 the merits or faults of their papers are their own. The zeal, 

 intelligence and earnestness which they have devoted to the 

 work will be sure to have produced valuable results. Doctor 

 Beede, it is hoped, will be able in future papers to complete the 

 review of the paleozoic invertebrates. 



At the present time, Mr. E. H. Sellards, assistant in the de- 

 partment of paleontology, has well along a work on the paleo- 

 zoic plants which, it is expected, will soon be published. 



The writer desires to thank Mr. Sydney Prentice, who has 

 made all the drawings of this volume, for the care and faithful- 

 ness he has given to the work. 



SAMUEL W. WILLISTON. 



