PREFACE. 



In the "American Journal of Science and Art," A. I). 1M7, Prof. 

 J. \V. Bailey, of Wesl Point, said : " With the exception of six or 

 eight, I am imt aware of any published account <>t' our Marine Alga. 

 Of Mm- fluviatile (fresh-water) Alga, I find no published notice, 



although they appear to have been studied with bo care by the 



indefatigable Schweinitz," ami at a little later date he adds: "It 

 appears that to Schweinitz is due the credit of being the first to collect 

 and to study any of our fresh-water Alga." I refer with all the 

 mure pleasure t" these remarks concerning the hit'- Rev. L. I>. von 

 Schweinitz, of Bethlehem, Pa., that he was a friend of my youth, and 

 the first t" draw my attention to the study of cryptogamous plants. 

 !t i- (inly proper that ample credit Bhould he given to this the first 

 collector "f our fresh-water Alga in this the first monograph published 

 in the United State-, mi that class of Alga known as Desmids. 



Nearly forty year- ago Prof. J. W. Bailey, contributed to the 

 "American Journal of Science and Art,*' two papers, one describing a 

 few new species of he-mid- from the Catskill mountains, and the other, 

 "Notes on the Alga of the United State-:*' following these we have, 

 "Microscopical Observations made in Smith Carolina, Georgia, and 

 Florida Smithsonian Institute. A.. D., 1850, 50 pp." These observa- 

 tions cover Infusoria and Alga, the latter comprising a list of one 

 hundred and twenty-five species, among which appear a few newly 

 discovered Desmids which are illustrated and described. 



Horatio C Wood, dr.. M. D., published in 1872, through the Smith- 

 sonian Institute, "A Contribution to the History of the Fresh- Water 

 Al'i'i of North America." In this publication Dr. Wood brought 

 ther all the recorded observations that had beeu made up to that 



