12 PREFACE. 



Six plates, illustrating the genera of the Cyperacecz or Sedge 

 Family, are now added to the eight which illustrate the Graminece 

 or Grasses, and the six which illustrate the Filices or Ferns and 

 their allies : all are from original drawings by Mr. Isaac Sprague ; 

 and they should render the study of these families comparatively 

 easy, even to the beginner. 



In other respects the changes in this edition are only in details, 

 and such as the progress of botanical knowledge, and the longer 

 experience of the author and his associates or correspondents in 

 teaching, have seemed to render necessary or advisable. 



I am newly indebted to DR. GEORGE ENGELMANN, of St. Louis, 

 for a revision of the account of Cuscuta and Sagittaria, &c., formerly 

 prepared by him, and for the complete re-elaboration of the genera 

 Callitriche, Euphorbia, Pinus, Juncus, and Isoetes. I have also to 

 express my special acknowledgments to my friends, DR. J. W. 

 BOBBINS, of Uxbridge, Massachusetts, who contributed the whole 

 article on the difficult genus Potamogeton ; to Mr. COE F. AUSTIN, 

 of Closter, New Jersey, who furnished that on the Lemnacece ; and 

 to Prof. DANIEL CADY EATON, of Yale College, who has entirely 

 re-elaborated the Ferns for the present edition. The Salicacece and 

 the genus Carex, as is well known, were contributed to the first 

 edition by my old friend and associate, JOHN CAREY, Esq., now of 

 London. Deprived of his further and important assistance, I have 



Eastern North America which have not been heretofore figured, by WM. S. SULLI- 

 VANT, LL. D. Imp. 8vo, with 129 copper-plates. 



Musci-Boreali-Americana, sive Specimina Exsiccata, etc. A second and en- 

 larged edition of the arranged collection of Mosses of the United States, pub- 

 lished by Messrs. STTLLIVANT and LESQUEREUX, of which the first issue was 

 noticed in the preface to former editions of the Manual. The present edition 

 comprises 536 species or varieties of Mosses, and is supplied by Mr. Leo Les- 

 quereux, of Columbus, Ohio, for $ 35 in gold, or 7 sterling. 



Lichenes Exsiccati, by Professor EDWARD TUCKERMAN, of Amherst College; 

 of which four vols. (small 4to) have already been issued. A small volume on 

 the Genera of North American Lichenes is now in preparation by the same author. 



Nereis Boreali- Americana, an account of the Marine Algae of the United 

 States, by the late Professor WM. H. HARVEY, a large quarto volume with fifty 

 colored plates, published by the Smithsonian Institution. 



