84 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



species here given, and would mislead if used for species of 

 other regions. Each distinction in the key being founded on a 

 single character, it ma)' sometimes happen that one will be led 

 in this way to a specific description differing in other characters 

 from the plant in hand ; in such case it may be that it is a 

 species new to this region, and reference should be had to more 

 general works. 



At the end of the descriptive part of the work will be found a 

 list of the works referred to, arranged alphabetically by authors, 

 the date being given after the author's name ; in the text the 

 reference will be by name and date only, full particulars of title, 

 etc,, being given in the list. This does not attempt to be a full 

 catalogue of works on American algae ; for an account of 

 these, published previously to 1889, see De Toni, 1889 ; for 

 works with special reference to American algae, see Tilden, 

 1895 ; later than these dates the bibliographical notes in Just's 

 Botanischer Jahresbericht, Nuova Notarisia, Botanische Cen- 

 tralblatt and Hedwigia will be useful, as also the Index to 

 American Botanical Literature in the Bulletin of the Torrey 

 Botanical Club. The labels of the several numbers in the Phy- 

 cotheca Boreali- Americana often have a pretty full bibliography 

 of the species. 



In nomenclature, the rules of the Vienna Congress have been 

 used as a basis ; but as these rules were adopted completely 

 only as to the higher plants, the question of a starting point for 

 the nomenclature of algae being referred to a future congress, 

 it has seemed unwise at present unnecessarily to disturb well 

 established names. As regards classification, the general ar- 

 rangement is that of Oltmanns, 1904, but with some variations 

 in detail. 



Anything ol the character of the present work, whatever 

 name appears as that of its author, represents, if it is of any 

 value, the work of many individuals. Limitations of space pre- 

 vent giving exact localities and collectors' names under the 

 several species, and so many have aided the writer by con- 

 tributions of material from localities that he could not himself 

 visit, that a general acknowledgement of their assistance must 

 suffice. But a few names must be mentioned. To Prof. W. G. 



