LETTEE OF TRANSMITTAL. xiii 



Survey, Whitfield's Spergen Hill fossils, etc., in the Bulletins 

 of the American Museum of Natural History, New York. I 

 have borrowed also from many other authorities; but all of 

 them are credited in the several places which their names and 

 figures occupy. 



Periodicals and volumes published privately I have abstained 

 from quoting, except Herr Zittell's invaluable Handbuch der 

 Palaeontologie, and then only such figures as Zittell himself 

 had borrowed from American works, and for the purpose of 

 bringing his great work to the attention of American students. 



The reader will usually find the authority in the southwest 

 corner of the cut; the formation (by number, from / to XVII) 

 in the northwest corner; the name of the State survey, volume^ 

 plate^ a.nd -figure^ at the bottom, or in the other two corners; 

 but the necessity for having the cut as small as possible, and 

 the irregular shape of the fossil figures,' made absolute unifor- 

 mity impossible. Proof reading at the distance of a hundred 

 miles involves typographical errors in spite of the greatest care- 

 fulness; and several of the figures went through the press at 

 last upside down ; but the fact can be recognized by the re- 

 versed lettering; in three cases figures have got under the 

 wrong namen, as noted in the errata. 



Although the most of this book has been prepared and written 

 by myself, I have received most valuable assistance from Mr. 

 George B. Simpson, in indicating and verifying synonyms, and 

 reexamining and renaming specimens in the palaeontologcal 

 collection of the survey ; also from Mr. Oliver B. Harden and 

 Mr. Edward B. Harden, in carding some of the figures, and writ- 

 ing out references, and proof reading so far as their regular 

 work in other department of the survey would permit. Besides 

 the drawing of typical specimens of new species by Mr. Simpson, 

 a number of copies of Prof. Hall's lithographic figures were 

 made for me by Mr. F. Van Iterson, of Hoboken, N. J. 



Copy for the whole of the second volume, N to Z, is ready 

 for the printer. 



Palaeontological experts with large libraries and collections 

 at their command will not value highly this local and partial 

 compilation, whose author has no standing among them, and can 

 give them no help in their arduous professional labours. But 

 they will recognize the value of this book as a first experimental 



