300 MOSSES AND FERNS CHAP. 



base has a pair of conspicuous stipules like those found in the 

 other genera. 



Kaulfussia cesculifolia is the sole representative of the family 

 Kaulfussiese, and differs very much in habit from the other liv- 

 ing Marattiaceae. The rhizome and leaf arrangement are not 

 unlike those of Dancea, but the leaf is palmately divided, and the 

 venation is reticulate, while the synangia are scattered. The 

 synangium is circular, or broadly oval in outline. (Fig. 166). 



The recently discovered Archangiopteris, (Fig. 168) is a 

 small Fern from southern China, which in habit resembles 

 Dancea. The sporangia, however, are more like those of 

 Anglo pier is. 



The Affinities of the Eusporangiate Filicinece 



In attempting to determine the affinities of the members of 

 this group, many difficulties are encountered. First, and 

 perhaps most important, is the small number of species still 

 existing, which probably are merely remnants of groups once 

 much more abundant. This is certainly true of the Maratti- 

 acese, and presumably is the case with the Ophioglossaceae as 

 well. In the former this is amply proven by the geological 

 record; but in the others the fossil forms allied to them are 

 very uncertain, and as yet poorly understood. In the Ophio- 

 glossaceae the series from Ophioglossum through the simpler 

 species of Botrychium to the higher ones, such as B. Virgin- 

 ianum, is complete and unmistakable, but when points of con- 

 nection between these and other forms are sought, the matter 

 is not so simple. 



Our still somewhat incomplete knowledge of the gameto- 

 phyte of the Ophioglossacese makes the comparison doubly 

 difficult. From the development of chlorophyll in the germi- 

 nating spore of B. Virginianum, as well as from analogy with 

 other Ferns, it seems probable at any rate that the subterranean 

 chlorophylless prothallium is a secondary formation, but this 

 cannot be asserted positively until the development is much 

 better known than at present, and its relation to the green pro- 

 thallium of the Marattiales and the thallus of the Hepaticse 

 must remain in doubt. The structure of the sexual organs and 

 development of the embryo point to a not very remote connection 

 with the former order, and in some respects also to the Antho- 

 cerotes. 



