THE AFFINITIES OF THE OPHIOGLOSSACE^ 

 AND MARSILIACE^. 



DOUGLAS H. CAMPBELL. 



The last ten years have been notable for many important 

 ■contributions to our knowledge of the pteridophytes, due in part 

 to a more exact investigation of many forms already studied, but 

 still more to a critical study of tropical types, which hitherto 

 have been studied more or less superficially, owing to the diffi- 

 culty of procuring suitable materials for complete investigations. 

 The fossil forms have also yielded much important material for 

 a better understanding of the affinities of some of the living 



The work has covered a wide field and comprises very valu- 

 able additions to our knowledge of the anatom\- and develop- 

 ment of many interesting types which were but imi)erfectly 

 known before. These investigations have adtled materially to 

 the data available for a critical comparison of the different 

 groups, and we are in a much better position than ever before 

 to understand the affinities of some of the more ])uzzliiig types 

 of pteridophytes. It must be admitted, howe\er, that the ton- 

 elusions of botanists in regard to the relationships of certain 

 groups are by no means entirely in accord. 



There are two orders of ferns about whose relationships there 

 has been a good deal of controversy, and it is the bearing of 

 some of the recent investigations upon these relationships to 

 which the writer would direct attention. The two orders ret erred 

 to are the Ophioglossaceae and the Hydropteridinea , esi-eeially 

 the Marsiliaceaj. 



The Ophioglossaceae constiti 

 ke plants, evidently closely 



