GENERA OF FERNS. 435 
Rhizoma creeping, thick and densely criniferous. Fronds 
tripinnate, smooth, ultimate segments dentate, the fertile por- 
tion slightly contracted, bearing the sori in thyrsiform clusters. 
Indusia coriaceous. 
Species. B. Culcita, Kaulf. 
Must. Hook. Gen. Fil. t. 60. A. 
Obs. The slightly oblong and coriaceous texture of the 
indusia, with the remarkable criniferous rhizoma, are the 
chief features that mark this beautiful fern. 
116. Dicxsonia, D’Hérit. J. Sm. 
(Balantii sp. Kaulf. Culcita, Presl.) 
Veins pinnate; venules simple, direct, their apices free and 
sporangiferous. Accessory indusium cucullate, larger than 
the special indusium, forming a reflexed unequal bilabiate 
cyst, constituting large globose sori. Receptacle elevated, 
globose. 
Rhizoma arborescent. Fronds 6i-tripinnate, smooth or 
scabrous, ultimate segments dentate, teeth soriferous. Indusia 
Examp. 1. D. arborescens, L'Hérit. 2. D. antarctica, 
Labill. 3. D. squarrosa, Sw. 4. D. levis, Hew. in Herb. 
A. Cunn. 5. D. Organensis, Miers herb. 
lilust. Hook. et Bauer Gen. Fil. t. 20. 
Obs. The genus Dicksonia was originally founded by L'Hé- 
ritier upon two species, natives of St. Helena and Madeira, 
the one having an arborescent caudex (or rhizoma) fifteen 
to thirty feet or more in height, and the other with a short 
thick creeping rhizoma. Subsequent discoveries have added 
about twenty species to the genus, which with a few excep- 
tions agree in their general habit and vascular structure of 
their fronds; but the greater number have a creeping rhizo- 
ma, and differ from the original type of the genus (D. ar- 
borescens), not only in that respect, but also in the special 
and accessory indusia being more or less connate, and form- 
ing a nearly entire circular cup; whereas in the species which 
