234 MOSSES AND FERNS chap. 



Leptosporangiatse include the single great homosporous order 

 Filices, and the two heterosporous famihes, closely related to 

 it, the Salviniacese and the Marsiliacese. These are usually- 

 classed together as a distinct order, the Hydropterides or 

 Rhizocarpese. 



The Filicine^ Eusporangiat^ 



The two orders, Ophioglossales and Marattiales, show 

 many evidences of being very ancient forms, and in several 

 respects seem to approach more nearly to the Hepaticae than any 

 other Pteridophytes. While they are different from each other- 

 in many respects, still there is sufficient evidence to indicate- 

 that they belong to a common stock to warrant placing them 

 near each other in the system. 



The Ophioglossales 



The three genera belonging to this order may all be united 

 in a single family, Ophioglossacese. 



The Gametophyte 



Our knowledge of the gametophyte of the Ophioglossacese 

 has been very much augmented during the past ten years. Jef- 

 frey (i) has described very fully the gametophyte of Botry- 

 chium Virginianum, and Lang (4) and Bruchmann (5) have 

 made out the most important facts in that of Ophioglossum and 

 Helminthostachys. Our earlier knowledge was based entirely 

 upon the fragmentary observations of Hofmeister (i) upon 

 Botrychium lunaria, and those of Mettenius (2) upon Ophio- 

 glossum, pedunculosum. 



The writer has succeeded in securing the earliest phases of 

 germination in two species, viz., Ophioglossum (Ophio-. 

 derma) pendulum and Botrychium Virginianum, as well as the 

 older prothallia of the latter. The germination in both cases 

 is extremely slow, especially in the former, where a year and a 

 half after the spores were sown the largest prothallia had but 

 three cells. Probably under natural conditions the growth is 

 more rapid. The spores of both forms show much the same 

 structure. The tetrahedral spores contain granular matter, 



