VI DIA'I'oAl AC!-;. K ()!' NORTH AMERICA. 



many others, all of whom have rendered valuable service as col- 

 lectors, as preparers of specimens or as students of the structure, 

 habits, growth and development of Diatoms. 



Among foreign writers who have described many North 

 American forms are Ch. Stodder, who described the diatoma- 

 ceous earth found at Randolph, Mass., Richmond, Va., and at 

 Santa Monica, Cal.; B. K. Greville. F. Kitton, C. Janisch, L. 

 Rabeuhorst, A. Gruuow and others are associated with species 

 found in western territories and waters from Vaucouvers Sound 

 and southward across the Continent to Campeachy Bay and the 

 Gulf of Mexico. 



Upwards of eight thousand species of Diatoms are recorded 

 in Chase's edition of Habirshaw's Catalogue of the Diatomacese 

 of the world, 1888. Of these, less than two thousand are North 

 American species, but the figures and descriptions of these are 

 scattered through many and rare volumes of Journals of Scien- 

 tific Societies, magazines, reports of expeditions, beside special 

 works: for which reason students find the literature of the Dia- 

 toms very difficult and costly to obtain. In the present volume 

 is collected the cream of what has been already written on the 

 subject, as well as the figures of all known North American 

 species together with the most approved system of classification. 



I follow the example of Adolph Schmidt in his Alias der 

 Diatomacean Kun.de in letting the figures suffice for a description 

 of the species. The Conspectus of the Families and Genera of 

 the Diatomacea- in this work, is that of Prof. H. L. Smith, of 

 Hobart College, Geneva, N. Y., originally published in The Lean. 

 January. 1872, and which Dr. H. Van Heurck has also adopted 

 in his Synopsis der Diaionu-i'* d<- 7>V////V/w. a few subdivisions of 

 genera being added. 



I gratefully acknowledge the very valuable assistance freely 

 extended to me by that veteran authority, Prof. H. L. Smith, to 

 whom I submitted the plates of this work prior to their being 

 photolithographed. I am also greatly indebted to Dr. H. H. 

 Chase, of Michigan, through personal correspondence and his 

 invaluable catalogue of the Diatomacese of the world. Nor can 

 I omit to mention Prof. J. D. Cox. of Cincinnati, Ohio, B. N. 

 Thomas, of Chicago, or Kain, of Philadelphia, Pa., all willing 

 friends in time of need. 



