ag 
of many localities in tropical America, also found in Trini- ` 
dad, it is peculiar for having two or more sori on some of 
the branches of the veins, Being arborescent, and the sori 
criniferous, has led several authors to refer it to the genus 
| Alsophila, but from which it differs in the vernation (base of 
the stipes), being criniferous, which is not the case with 
true Alsophila. The evidence of its being a tree Fern rests 
entirely on Wildenow’s description, which says “caudex 
erectus arboreous,” but according to a plant at Kew, which 
in 1864 had fronds 2 to 3 feet high, the caudex was decum- 
bent, but which probably only required time to assume an 
arboreous character; whichever it may be, I find it difficult 
to point out its relationship with any sequence of genera, 
except that it may be ranked with Lophosoria in Phegopteris. 
Sp. A. blechnoides, Klot. in Linn. (Metaxya rostratum, 
Hook. and Bauer.; P. Parkeri, Hook. and Grev., t. 232; Al- 
sophila blechnoides, Hook. Sp. Fil.) 
Nors.—In the preceding tribes the sori are discal ; and. 
marginal in the six following. 
J CHARACTERS OF TRIBES AND GENERA. 
Tribe 16.—DICKSONIEJE. (Plate 16.) 
. Vernation fasciculate, decumbent or erect, and becoming 
arborescent. Sori marginal, globose, or transverse ob- 
long, furnished with an interior attached special indusium, 
` which connives more or less with the changed indusioid ` 
. margin of the frond, the two forming an urceolate, be 
valved, marginal cyst, containing the sporangia. 
Oss.—Hitherto I included under this tribe the genera 
` Sitobolium, Lindscea, Microlepia, and other allied genera, — 
which, although agreeing in the technical character of | 
their sori, nevertholess differ widely in habit, so much so, 
