PREFACE 



Probably no continent is more jiroductive of well-preserved Paleozoic 

 bracliiopods than Kortli America. Througbont the vast territory of the 

 United States which is drained by the Mississipi)i River the strata have 

 sufl'ered little change, and it is this region which has furnislied nearly 

 all the material, from the Middle Ordovician to the top of the Upper 

 Carboniferous. The numerous species of American Cambrian brachio- 

 pods which are found scattered along the margins of this great interior 

 plateau and throughout iSTew Brunswick have also aided largely in 

 determining the evolution of the class. To Mr, Walcott, Director of 

 the United States Geological Survey, much honor is due for making 

 clear the structure of brachiopods from this system. 



The present synopsis was begun in Cincinnati eleven years ago, 

 while the writer was engaged in paleontologic work with Mr. E. O. 

 Ulrich. In 1887, when the list had increased to about 700 cards, the 

 position of assistant to Prof. James Hall was entered upon. A nearly 

 complete library of American paleontologic literature thus became avail- 

 able to the writer, and during the next two years the greater part 

 of his leisure was devoted to recording brachiopod literature. The 

 large private collection of brachiopods belonging to Professor Hall, 

 together with the many public and private collections then under inves- 

 tigation by Hall and Clarke, also afforded the writer abundant facilities 

 and a rare opportunity for the study of this class. Every occasion was 

 embraced to examine into the synonymy suggested by authors, and in 

 this work it is believed much has been attained. In addition to the 

 above collections and to the material in his own possession, the writer 

 has also studied the speciuiens belonging to this class in the American 

 Museum of oSTatural History, Yale University Museum, Cincinnati 

 Society of Natural History, and the United States National Museum. 

 In 1890 the i^resent catalogue comprised uj)ward of 3,o00 cards, ar- 

 ranged in boxes having a united length of about 4 feet. It now includes 

 nearly 10,000 references relating to North and South American fossil 

 brachiopods. 



It is believed that with the exception of local faunal lists all the lit- 

 erature of North and South America pertaining to this subject is 

 recorded in the following synopsis. Much possible synonymy which 

 the writer could not satisfactorily determine is noted under "Observa- 

 tions." The complete known distribution of widely dispersed species 



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