250 4 



at thai lime I could not venture to undertake the work myself, though after 

 Dr. RosENSTor.K of Gotha had sent me his Brazilian "opposita" forms for examina- 

 tion I felt inclined to make a trial. As further, the Museums of Berlin, Stockholm 

 and Copenhagen and also Dr. Chiust have on my request most kindly placed their 

 large collections at my disposal, I obtained a material, which has probably never 

 before been collected together. It includes more than 1200 specimens, amongst 

 which are, a few excepted, type specimens of all the hitherto described species 

 of the group of D. opposita. I really only want the species described by Baker 

 and a few described by Jenman and Sodiuo, as authentic specimens of most of the 

 new species of these latter authors are found in Herb. Berol. and Herb. Ciirist. 



For the great kindness shown me by the curators of these museums and the 

 two pteridologists Dr. H. Christ and Dr. E. Rosenstück I wish to express here my 

 most sincere thanks. I must also thank Dr. E. Bayer, Curator of the "Museum 

 des Königreiches Böhmen" of Prague for his kindness in sending me two type 

 specimens of species described by Presl. Lastly it is a special pleasure to 

 thank Prof. Hieronymus, Berlin, and Prof. Lindman, Stockholm, for their help in 

 different ways. 



The limitation of the group of species I here take up for monographic treat- 

 ment is somewhat difficult. Briefly, it includes those species of Dnjopteris with 

 free veins which have a "lamina bipinnatifida ad basin attenuata" and generally 

 simple veins. This group passes gradually to the group, in which the typical spe- 

 cies is D. patens. The species belonging to the latter, which also have a "lamina 

 bipinnatifida venis liberis simplicibus", still diller partly by having non-reduced 

 or only a little shortened lower pinnæ, but generally a pronounced deltoid lamina, 

 partly in their having the basal pair of veins of a segment running out into the 

 sinus itself between the segments, whereas in the opposita forms they reach the 

 edge more or less above the sinus. D. diplazioides is here the only exception, but 

 even in this species the ends of the two basal veins do not meet each other, 

 whereas in the group of D. patens they often run together. Most often the 

 species of the group of D. patens have also a larger, persistent and generally very 

 hairy indusium, while the species allied to D. opposita are either exindusiate or 

 furnished with a very small, deciduous indusium, just as the sori generally are 

 small consisting only of a few loosely attached sporangia. 



The group of D. opposita, according to the above given limitation, thus in- 

 cludes species of the old genera Lastrea, Phegopteris and Leptogrammn. In working 

 up these species it has become perfectly clear to me that Phegopteris may not 

 only not be considered as a genus, which American pteridologists always maintain, 

 but even not as a subgenus. The species of Phegopteris must be placed amongst 

 the other species of Eiidrgopteris, as Diels has already tried in "Die natürlichen 

 Pflanzenfamilien", and which has been done by Hieronymus, Christ and Rosen- 



