288 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VOL. V. 



is the case is rendered probable by the strict locaHzation of the antheridia 

 on the antheridial ridge, and by the occurrence of the reproductive 

 organs on the upper surface of the gametophyte. It is interesting in 

 this connection to note the scattered disposition of the antheridia in the 

 very young prothallus; for this is jjrobably to be regarded as a primitive 

 feature. An embryological comparison between the two forms is not 

 possible, as the embryology of B. Lunaria is at present unknown. The 

 young sporophyte of ^. virginianuvi, in that it is attached to the upper 

 surface of the prothallus, and has a completely developed and assimila- 

 tory cotyledon, differs from the sporophyte of B. Lunaria. The young 

 spore-plant also remains much longer attached to the gametophyte than 

 is the case in the latter species. B. virginianuvi seems, of all the 

 representatives of the genus in Canada at least, to be the most com- 

 pletely adapted to modern conditions ; for it is everywhere abundant in 

 rich woods, and always outnumbers the other species. 



The prothallus of Ophioglossum pedunculosuni does not very closely 

 resemble that of B. virginianum. The presence of a primary tubercle 

 and the formation of green prothallial lobes are its characteristic 

 features. It should be remembered, however, that within the single 

 genus Lycopodinin, L. annotinuni resembles in its prothallus B. virgin- 

 ianum and B. Lunaria, whilst L. cernuum and L. inundatuni have a 

 gametophyte like that of Ophioglossum pedunculosuni. It is possible 

 that a species oi Botrychium may yet be found in which the prothallus 

 is like that of Ophioglossum pedunculosuni. The ajitheridia and anthero- 

 zoids of the present species quite exactly resemble Mettenius' description 

 of those of Ophioglossum pedunculosuni. The archegonia correspond, 

 too, in so far as the earlier description offers points of comparison. In 

 the development of the embryo, the account of Mettenius is rather too 

 meagre to allow of any exact inferences in regard to points of likeness 

 in the successive phases of segmentation. The young sporophyte of 

 Ophioglossum pedunculosuni develops its cotyledon early, and the 

 primary root is slow in pushing its way out, which exactly reverses the 

 course of events in B. virginianum and probably also in B. Lunaria. 



Bower34 has recently fully discussed the relationships of the Ophio- 

 glossacecE to the other groups of the Pteridophyta. He comes to the 

 conclusion that the ventral fertile leaf-segment of the Ophioglossacea^ is 

 the morphological equivalent of the single ventral sporangium of the 

 homosporous LycopodinecB, and derives it from the former by a process 

 of septation and branching. He also compares the two groups in 



34. Studies in the morphology of spore-producing' members. Part 2. 0/A/cif/os.f(7fp«', p. 56, et seq. 



