LETTER OF TRANSMITTAL 



STATE GEOLOGICAL SURVEY 

 UNIVERSITY OF ILLINOIS, FEBRUARY 15, 1913. 



Governor E. F. Dunne, Chairman, and Members of the Geological Survey 

 Commission: 



GENTLEMEN : When the present Survey was created in 1905 the Geolog- 

 ical Commission adopted a balanced program which emphasized economic 

 work of immediate, though perhaps temporary, value; it nevertheless 

 included deep scientific research into fundamental problems, having only 

 indirect bearing on economic geology of the State. 



The Survey has now published nineteen bulletins and many useful maps 

 which have served an increasing public demand. Nine other reports are 

 in manuscript form for early printing. I now have the pleasure of trans- 

 mitting to you an illustrated report on the Mississippian Brachiopoda, 

 by Professor Stuart Weller of the University of Chicago, and I recommend 

 that it be published as the first of the scientific monographs of the Survey. 



Because of the highly technical character of this report it is perhaps 

 fitting to state that an understanding of our geological formations is based 

 not only on their materials but also on their included fossil remains, 

 which indicate the relative time-periods during which the rocks were 

 deposited. The Mississippian formations have their type localities in 

 Illinois and the immediately adjoining states of the Mississippi Valley. 

 The study of these strata for more than half a century has been attended 

 by considerable confusion. Professor Weller 's work, extending over a 

 period of eight years, has solved many of the difficulties of stratigraphy 

 and paleontology. His monograph will be gratefully received by profes- 

 sional geologists throughout the world. 



Very respectfully, 



FRANK W. DEWOLF, Director. 



