10 MISSISSIPPIAN BBACHIOPODA 



Under the discussion of each species the name of the geological forma- 

 : tion or, form-atiojis of whose fauna the species is a member, has been 



fe'corded*, but : no' attempt has been made to record all the localities from 



WMoh tfte ^species is known. In the explanation of the plates, however, 

 ' the exact locality of the specimen illustrated has always been mentioned. 



The material used in the preparation of the report has been drawn from 

 all available sources. The collections in the Walker Museum of The Uni- 

 versity of Chicago have been a most prolific source of supply because of 

 the presence of the Gurley collection and the James Hall collection, both 

 of which are rich in types of Mississippian fossils, as well as of several 

 smaller collections, of which the Sampson collection and the Van Home 

 collection especially have supplied important specimens. Through the 

 kindness of Dr. A. R. Crook, curator of the Illinois State Museum of Nat- 

 ural History, several type specimens have been loaned for study and illus- 

 tration from the collections of that institution. Dr. E. 0. Hovey of the 

 American Museum of Natural History in New York City has been most 

 generous in his willingness to send many important type specimens to the 

 author for study and illustration. The many types of species described 

 by Winchell and by White and Whitfield, preserved in the White collec- 

 tion in the museum of the University of Michigan, have been made avail- 

 able for study and illustration through the co-operation of Dr. E. C. Case. 

 Dr. R. S. Bassler has generously loaned certain material from the U. S. 

 National Museum in Washington. Besides these curators of great public 

 collections, private collectors have not been backward in furthering the 

 preparation of the report. Prof. R. R. Rowley, of Louisiana, Missouri, 

 who has described many species of Mississippian brachiopods, has gener- 

 ously placed in the hands of the writer either the types or authentic speci- 

 mens of all his species, which have been used for the illustrations and as 

 the basis for the definitions here published. Mr. D. K. Greger of Fulton, 

 Missouri, has made his extensive collection of Mississippian brachiopods 

 freely available to the writer in the preparation of the report. To all 

 these curators and collectors I wish to express my great obligation, for 

 without their co-operation the report could never have been made as com- 

 plete as it now is. 



No claim of absolute completeness can be made for any work of this 

 sort. Many species were described entirely without illustrations by 

 earlier workers in the subject, and in many instances the original types of 

 these species have been lost or destroyed. It has been possible to recog- 

 nize many such species from the definitions or from the definitions along 

 with specimens more recently collected in the original localities, but there 

 still remains a considerable number of such species which have not been 

 recognized, some or all of which may still be cleared up through future 

 collection and study. It is also to be expected that further work in the 

 field may bring to light additional undescribed species. 



