26 Repoet of the StxIte Geologist. 



pend all work upon the volume ; so that this chapter, bringing 

 the text up to 350 pages, together with accompanying and con- 

 cluding matter, was laid over to the present year. 



In the original scheme of the work on the Brachiopoda the 

 generic descriptions were to be accompanied with illustrations of 

 the microscopic structure of the shell, but it was found incon- 

 venient to accomplish this plan during its progress ; though a 

 large number of sections were prepared for microscopic study., 

 This part of the work is postponed for the present, and probably 

 will not be taken up again by the writer. 



The great length of time since these studies were resumed in 

 1888 has enabled those assistants who were with me in the earlier 

 preparation of the work to advance their investigations in the 

 same line of concept, and to anticipate some of the results which 

 have been reached in these volumes. While the final result in 

 this direction is still distant, it is encouraging to see the work 

 advancing in what the writer believes to be the only true method 

 of studying every class of organisms. 



In the preface to Part I of Yolume YlII the author made 

 acknowledgments to many personal friends, to collectors of fos- 

 sils, to museums a ad geological surveys ; he wishes to repeat 

 these acknowledgments in the preface to Part II, since this will 

 probably be his last opportunity of connecting their names with 

 the progress of the ^' Palaeontology of New. York." 



During the 51 years which have elapsed since the com- 

 mencement of this work, I have had many assistants who directly 

 or indirectly have aided in, or have contributed to, its progress. 

 Among the earliest of these was Mr. Fielding B. Meek (after- 

 ward Palaeontologist to the United States Geological Survey of 

 the Territories), whose services were largely given to the draw- 

 ings for the plates of Yolume III, which were lithographed by 

 Mr. Frederick J. Swinton, the latter continuing his connection 

 with the work till 1872, enriching the volumes by his excellent 

 artistic work. During the early part of the same period Mr. 

 Ferdinand Y. Hayden, who subsequently became Director of the 

 U. S. Geological ISurvey, was my assistant, and, together with 

 Mr. Meek, made a survey of the Mauvaises Terres of Nebraska, 

 at my personal expense. Dr. Charles A. White, now of the 

 National Museum at Washington, who had been my assistant in 



