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THE AMERICAN NATURALIST. [Vol. XXXVIII. 



whose affinities to the other pteridophytes have been much dis- 

 cussed. They are generally considered to belong to the Fih- 

 cinece, or ferns with which they agree in their general structure. 

 The writer has expressed the opinion that the sporangium of 

 Ophioglossum represents the lowest type found in the fern 

 series. This conclusion is based upon the structure of the living 

 forms, as the Ophioglossaceae are almost unknown in a fossil 

 condition, perhaps owing to the soft tissues which characterize 

 them. These would hardly be preserved as fossils except under 

 the most favorable conditions. 



As is well known, the Ophioglossaceae differ from the typical 

 ferns in the position of the sporangia, which are borne upon a 

 peculiar structure (sporangiophore) arising from the inner sur- 

 face of the leaf, either directly from the lamina or from the 

 petiole. The sporangiophore may be a simple spike with two 

 rows of large sporangia scarcely projecting at all, or it may 

 be much branched and the numerous sporangia quite distinct 

 and even stalked. {Campbell, Mosses and Ferns, p. 296.) The 

 former structure occurs in Ophioglossum, the latter in Botrychium 

 and Helminthostachys. The simpler species of Botrychium, such 

 as Botrychium simplex and Botrychium lunnria, form a transition 

 between the type of Ophioglossum and the larger species of 

 Botr\ chiuni and Helminthostachys, in which both the sterile and 

 tertile leaf segments are much branched, and the free sporangia 

 bear a certain resemblance to those of Osmunda or Angiopteris. 

 It IS possible that the latter types, or at any rate Osmunda, may 

 h.ive arisen from forms like Botrychium or Helriiinthostachys, 

 through which the)- would be connected with the more primitive 

 type ol sporan-ium found in Ophioglossum. 



Much the most important recent work upon the sporangia of 

 these puz/ling tnrms is that of Bower ("Studies in the Morphol- 

 ogy ..t Spnre-l'nKluoing Members " ; BJiil. Trans., 1894-1903, 

 1S5 106). wlinse views as to the relationship of the Ophio- 

 gloss:iee;e ditfcr radically from those of most students of the 

 pterKloi)hytes. ilc considers the whole spike of Ophioglo.ssum 

 as the equivalent ot a single sporangium of Lycopodium, pro- 

 duced by growth and scptation. from an originally unilocular 

 structure. He is not inclined to admit any direct relationship 



