PKEFACE. 



In 1848 William S. Sullivant published, in the first edition 

 of Gray's Manual of Botany, descrijjtions of two hundred 

 and five species of Mosses and sixty-six of Hepaticie. In the 

 second edition of the same Manual, published in 1856, four 

 hundred and ten species of Mosses and one hundred and 

 seven of Ilepaticoe were described by him, with the addition 

 of eight fine plates for the illustration of the more important 

 genera.* This second edition becoming soon exhausted, Mr. 

 Sullivant, urged, by the friends of American botany to piib- 

 lish, in a separate volume, a Manual of American Mosses, 

 decided to begin the preparation of such a work in connec- 

 tion with the present writer, who had been since 1848 his 

 constant assistant in bryological research. A large amount 

 of material had been collected, the new mosses continually 

 received had been examined and described, and much pre- 

 paratory labor had thus been done wlien, in 1872, my sight 

 partially failed me, and a few months later Sullivant's noble 

 career was closed by death. 



The bryological collections of Sullivant, together with his 

 library and his manuscript notes, had been bequeathed to the 

 Harvard University Herabrium, and at the suggestion of Prof. 



* Separate issiies of both of these editions were made under the title of 

 "Mnsci and Hepaticse of the Northern United States," the last of wliich 

 reprints (containing some additions) is the work cited throughout the follow- 

 ing pages as " Sullivant's Mosses of the tTnited States." 



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