l896-97.] THE GAMETOPHYTE OF BOTRYCHIUM VIRGINIANUM. 289 



regard to the structure of the vegetative organs of the mature sporo- 

 phyte, and finds that in this respect they also show a marked resem- 

 blance to one another. Lastly, the organization of the gametophyte 

 and the development of the sporophyte, are discussed in the same con- 

 nection with a like conclusion. 



It is only necessary in considering the results of the present investi- 

 gation, to examine the latter features. In regard to the structure of 

 the prothalli, the two groups certainly do present marked likenesses; e.g., 

 the gametophyte of Ophioglossuui pedunculosuin to those of Lycopodium 

 cernuum and L. inundatiini, and the gametophytes of B. Lunaria and 

 B. virginianum to that of Z. annotinuvi. It is quite possible, however, 

 that the resemblance in these cases is due to a similarity in environment. 



The male organs of the two groups are in some important features 

 quite different. The antheridiiim has a double outer wall in the 

 OphioglossacecE and the antherzoids are spiral and multiciliate. In the 

 homosporous Lycopodinece, the antheridium has a simple outer wall, and 

 the antherozoids have the general configuration and the two cilia of the 

 antherozoids of the Bryophyta. 



The archegonia of B. virginianum at least, resemble those of the 

 FilicinecB, (excluding Isoetes, which probably does not belong here), in 

 having a basal cell and a single binucleate canal-cell, or at most two 

 neck canal-cells. On the other hand the Lycopodinece and EquisetacecE 

 are without the basal cell and have a decided tendency to increase the 

 number of cervical canal-cells. Too much importance should not, how- 

 ever, be attached to these structural features of the archegonia. 



The embryo of B. virginianum and apparently that also of 0. 

 pedunculosum, lacks the suspensor and primary sporophytic tubercle 

 which are so characteristic of most oi\^Q.\sosf^oxo\x's> LycopodinecE, and in 

 these defects resembles the Filicinece. So far as the facts in the case of 

 B. virginianum go, it seems probable that the Ophioglossacecz are much 

 more closely allied to the eusporangiate Filicinece than to the isosporous 

 Lycopodinece, although they may be possibly the nearest of the mega- 

 phyllous Pteridophyta to that group. In all probability, the Ophioglos- 

 sacecs are more primitive than the Marattiacece which they in some 

 respects resemble. 



As a result of the fuller knowledge in recent years of the segmenta- 

 tation of the embryo of the Pteridophyta, it is scarcely possible to retain 

 any longer the conception of octants propounded by Leitgeb and others 

 when the leptosporangiate/^z7/«Wi^ were practically the only ferns in which 



