PREFACE. IX 



gingly furnished me with copious translations from German 

 works. 



To no one are my obligations greater than to Mr. Borrer : 

 by his advice and assistance the work has been freed from 

 many defects that would have impaired the utility which I 

 trust it may now possess. I gladly return my thanks also 

 to my valued friend the Rev. H. Penneck, who has afforded 

 me his assistance throughout its progress and in its careful 

 preparation for the press. 



My thanks are due likewise to many other friends, for the 

 interest which they have taken in this publication, and for 

 their exertions to secure me from pecuniary risk ; especially 

 to Mrs. Griffiths, Miss Warren, Professor AUman, Mr. An- 

 drews, Professor Balfour, Mr. Coates, Mr. R. Q. Couch, Mr. 

 Dillwyn, Mr. P. Grant, Dr. Greville, Mr. Gutch, Mr. W. 

 Hanson, Professor Harvey, Rev. D. Landsborough, Mr. Mog- 

 gridge, Mr. Moore, Dr. Shapter, Mr. W. Thompson, Mr. 

 Topping, Mr. Tudor, and Mr. Williamson. 



I have to apologize for the long delay in publishing. It 

 has been caused partly by ill health, but chiefly by the con- 

 tinual discovery of additional matter and my wish that no 

 labours on my part should be wanting. When however I 

 state that I have thus been enabled to add the descriptions 

 of a large proportion of the species and of one-half of the 

 sporangia, besides the Appendix of foreign species, and at 

 least ten plates, I may be permitted to hope that the Sub- 

 scribers will readily excuse a delay which has so materially 

 increased the extent of the work without increasing its 

 price. 



