PREFACE. 



The literature of systematic natural history has become so voluminous that it is 

 almost impossible for the student to attain good results without the aid of some kind 

 of a compilation. In Paleozoic paleontology the need of such an index is perhaps 

 greatest for the fossils of the Ordovician, Silurian, and Devonian periods for the 

 reason that the Carboniferous has been covered up to 1898 by Weller's Bibliographic 

 Index of North American Invertebrates (Bulletin 153, United States Geological 

 Survey) , and the numerous monographs of the Secretary of the Smithsonian Institu- 

 tion upon Cambrian geology and paleontology have assembled the fossils of that 

 period. Dr. E. M. Kindle, while a member of the United States Geological Survey, 

 prepared an index of Devonian fossils which will probably be published in the 

 future. In the course of work upon the paleontologic collections of the United 

 States National Museum the present author has specialized upon the Ordovician and 

 Silurian, and it therefore became appropriate for him to prepare the bibliographic 

 index which is herewith placed at the service of his fellow workers. 



The great amount of labor required to complete an index of this size and character 

 in a few years is very evident, and the work could not have been brought to a 

 speedy conclusion had the author not had the help of two indefatigable and intelligent 

 assistants, Miss Florence George and Miss Adelaide C. Quisenberry, to both of whom 

 he is under great obligations. The refinement of stratigraphic designation consequent 

 on the great advance in knowledge of Ordovician and Silurian stratigraphy in the 

 last decade has necessitated a careful examination of all described fossils in order to 

 locate them accurately in the time scale. In this work and also in the task of 

 clearing up the synonyms the author is indebted to many friends for generous help, 

 particularly to Dr. Rudolph Ruedemann, Mr. Frank Springer, Dr. P. E. Raymond, 

 and Prof. W. H. Twenhofel. To Dr. E. O. Ulrich, whose knowledge of American 

 Paleozoic paleontology and stratigraphy, whether in manuscript form or otherwise, 

 has ever been at the command of the writer, he is under special indebtedness. The 

 writer has also had access to a set of references to American Paleozoic fossils covering 

 part of the literature up to 1906, prepared under the direction of Prof. Charles 

 Schuchert by Miss M. W. Moodey and Mr. J. M. Nickles. This set was of greatest 

 use for its foreign generic references, but in order to insure as few errors as possible 

 these references were again checked up with the literature covered by them. 



The terms Ordovician and Silurian in the title of this work are employed in a 

 broad sense, so as to include formations which, although considered of Cambrian or 

 Devonian age by some, are still placed in the Ordovician or Silurian by others. The 

 particular cases in the Siluiian are those of the upper Monroan and the Keyser forma- 

 tions, both of which the author would place in the Devonian. With the Ordovician 

 the author has catalogued the Ozarkian and Canadian faunas, both of which divisions 

 are regarded by Ulrich, Schuchert, Walcott, and others, the writer included, as of 

 systemic value. In fact, then, the present index is intended to cover all American 

 fossils which are known to occur in formations regarded as probably younger than 

 those which are definitely decided to be of Cambrian age, and older than those now 

 generally considered to belong to the Devonian period. 



VII 



