VIII PREFACE. 



Every effort has been made to eliminate errors, but it is inevitable that many will 

 be found. As the author intends to keep this index up to date for use in the United 

 States National Museum, all corrections will be greatly appreciated. A chapter 

 devoted to the literature of American Ordovician and Silurian paleontology was 

 prepared for this work, but was omitted when it was found that this subject will be 

 included in a forthcoming bibliographic publication by the United States Geological 

 Survey. 



The citations have been brought up to the close of 1914 with the exception that 

 two important monographs (Schuchert, Revision of Paleozoic Stelleroidea, Bulletin 

 88, United States National Museiun, and Springer, Monograph Crinoidea Flexibilia, 

 Smithsonian Institution), then in press or ready for publication, were included. 



Following the bibliographic list proper which makes up the greater part of the 

 work (pages 1 to 1342), the author has added an index of specific names (pages 1343 

 to 1406), showing under what generic or other combination any particular name has 

 been employed. Then, in order that the biological classification of any doubtful 

 genus may be readily ascertained, a biological classification (pages 1407 to 1428) and an 

 alphabetical list of genera (pages 1429 to 1440) are given. Finally, as an aid in recalling 

 the position of the many geological formations cited, an alphabetical list of American 

 Ordovician and Silurian formations, indicating their approximate place in the time 

 scale (pages 1511 to 1521), and correlation tables covering the most important areas of 

 fc-siliferous rocks, are given. With the help of these several features, in addition to 

 the bibliographic references, it is believed that all the needs of the student with one 

 exception are covered. This exception is the failure to indicate the characteristic 

 species of each formation in the faunal lists. As knowledge of the early Paleozoic 

 faunas increases it is becoming more evident that a species is characteristic of a 

 formation only in a certain area of deposition and when considered in connection 

 with the associated organisms. As the origin of the fauna, the lithology of its inclos- 

 ing sediments, and still other factors must also be considered in determining such 

 species, it has not seemed advisable to attempt to indicate them at present. 



The bibliographic citations are abbreviated as far as possible without sacrificing 

 clearness, and the horizon and locality of each species are condensed into as few words 

 as needed. The type locality is cited first, and in cases where a species occurs in 

 several formations the name of the particular formation follows in parenthesis each 

 locality listed. It will be noted that this index is also a register of the types of Or- 

 dovician and Silurian fossils contained in the United States National Museum. The 

 type terms holotype, paratype, and cotypes, for primary types, and plesiotypes, for 

 all supplemental types, employed throughout this work are those adopted in the 

 division of paleontology in the United States National Museum. All valid species 

 are printed in heavy-faced type. The cross references are condensed as much as 

 possible, and in cases where the generic cross reference will suffice for the species 

 under it, those for the latter are not given. 



