PREFACE 



The papers herewith pubHshed are arranged essentially in the 

 order of their presentation as indicated in the general account of 

 the Twentieth Anniversary Celebration published in the Journal of 

 The New York Botanical Garden for October, 1915. Three of 

 the papers presented are here omitted for the reason that they 

 have been, in substance, already published elsewhere in accordance 

 with prior engagements. " Collybia in North America," by W. A. 

 Murrill, was essentially a summary, along statistical and geo- 

 graphic lines, of the monograph of the genus Gymnopus {Collybia) 

 which subsequently appeared in the North American Flora 

 (9: 352-374- 7 Je 1916). The main facts of the paper by R. S. 

 Williams on "Philippine Island mosses collected by J. B. Leiberg" 

 are to be found in a paper entitled "Mosses of the Philippine and 

 Hawaiian Islands collected by the late John B. Leiberg," published 

 in the Bulletin of the Torrey Botanical Club (42: 571-577. 13 N 

 1915)- Likewise, the substance of the paper by B. O. Dodge on 

 the "Influence of the host on the morphology of the roestelia," 

 appeared in the Bulletin of the Torrey Botanical Club (42: 519- 

 542. pl. 28, 29. 5 N 1915) under the title, "The effect of the 

 host on the morphology of certain species of Gy mm sporangium:' 

 Six other papers actually read are omitted because of obligations 

 to publish elsewhere, or because they were considered by their 

 authors to be too incomplete or preliminary to justify publication 

 at the present time, or for other reasons. Of the papers read by 

 title, only one (that by W. J. Beal) is included in the present 

 volume. 



Marshall A. Howe, 



Editor 



