PREFACE. 



The Science of Geology rests upon the fossil contents of the rocks, 

 and, therefore, there can be but little knowledge of the science without 

 a knowledge of the fossils. Every one professes to take an interest in 

 Geology, although the complaint against the technical names is quite 

 general. This work may be regarded as a compilation of these technical 

 names in alphabetical order, with the signification of each, and in this 

 respect, it is a dictionary adapted to the use of every one, and designed 

 to remove the objections against the hard words used in the science. The 

 references to authors and publications are for the special benefit of the 

 describers of fossils and the students of palseontology, while the Groups of 

 rocks are given for the convenience of collectors and students generally. 

 The general plan of the work will be, at once, apparent to the reader; 

 a few remarks, however, in regard thereto, may not be inappropriate. 



The state of the science, at this time, does not admit of a very great 

 degree of certainty in the arrangement of Palaeozoic Fossils into fami- 

 lies ; such arrangement must, therefore, be regarded as more or less pro- 

 visional. And, in this work, where a class could not be arranged into 

 families already limited and defined, with approximate correctness, the 

 attempt has been omitted. No new families have been proposed, with 

 the exception of three names, followed by the provisional interrogation 

 point in the Class Echinodermata. The new family names in the Class 

 Lamellibranchiata are used by Prof. James Hall in the fifth volume of the 

 Palaeontology of New York. 



Each generic name is followed by the name of the author, the date 

 of the first publication, the title of the book in which it first appeared, 

 which is generally abbreviated, and the etymology of the word, which is 

 included within brackets. Valid names are printed in Roman letters. 

 Generic names, preoccupied, never defined, and where the fossils are 

 unknown in American palaeozoic rocks, or the names invalid for any 

 other reason, are italicized. The generic name always begins with a 

 capital letter, whether it is a valid or invalid name. 



Each specific name, or as it was formerly, called the trivial name, is 

 followed with the name of the author, the date of the first publication, 

 the title of the book in which it appeared, which is generally abbreviated, 

 the Group of rocks in which the fossil is found when the Group is known ; 

 but otherwise the formation alone is given, and the signification of the 



