RADULA. 321 
juniora elongato-campanulata, rarissime inveniuntur perfecte matura 
eddem forma. Calyptra claveeformis. Capsula oblongo-cylindrica. 
Andreecia in ramis terminalia teretia; bracteze 3-15-juge, equitantes 
concave subequilobe. 
Var. brachycalyx. Forma pulchra flavida bipinnata. Folia caulina valde 
recurvo-assurgentia, minus opaca. Perianthia brevia, lata, anguste 
obconica poculeformiave, aliis paucis autem normali longitudine 
immixtis. 
This is the only Radula which grows uniformly and solely on living 
leaves, whether of trees and shrubs or of robust perennial herbs, such as 
Aroids and Marants, or of ferns, It abounds throughout the Amazonian 
plain, from Para to the sources of the Negro and Orinoco, and to west- 
ward it ceases in the first undulations of the Andes, at Tarapoto in Peru 
and on the river Bombonasa in Ecuador: that is, below 2000 Eng. ft. If 
any described species, it can only be the Mexican R, flaccida L. et G., 
which grows on leaves of “ Psychotrie cujusdam,” and therefore in a warm 
climate, for no Pyschotria ascends the mountains. The leaves of R. 
flaccida, however, are said by Gottsche to be twice as long as broad (+ x 
4 lin., $ x } lin.) and to be merely obtuse, whereas our plant has them 
nearly, or quite, as broad as long, and occasionally the breadth at the 
very base is greater than the length, while the apex is widely rounded or 
subtruncate. These differences rendering its indentification with the 
Mexican plant doubtful, I have called it in my Mst. R. folvicola. 
I gathered specimens in perfect state in a vast number of localities, but 
after sedulously comparing them, I must reduce them all to a single 
species, which varies mainly in the length of the perianths and of the 
male spikes. When young the perianth is narrow-campanulate, but 
rarely preserves that form at maturity, and usually lengthens out until 
it assumes the shape of a trumpet or club, 3 or 4 times as long as broad. 
Where a great majority of the perianths stop considerably short of the 
normal elongation, we have the rare variety brachycalyx, which, however, 
differs in no other respect from the typical form. The ¢ spikes vary 
greatly in length, even on the same plant, and I have seen them with as 
many as 15 pairs of bracts, but never with fewer than 3 pairs. Parallel 
differences are observable in several other Radulw, and the length of the 
verianths, or of the ¢ spikes can never be relied on as aspecific distinction 
ntil the limits of its variation have been accurately ascertained.* 
8. RapuLta AMAZONICA Spruce. 
Hab. per sylvam Amazonicam ad arbores saxaque frequens. Caripi, prope 
Para, ad rupes maritimas. San Carlos, aliisque locis secus fl. Negro, 
in cortice. Ad fl. Orinoco supra cataractas, in cortice. 
F lobus 1°3 x 1°15, lobulus 5 K 5; c. yk 3 per 2°8 & 1:1™™, 
Fulvo-viridis, in plagas latas effusa. Caules circiter bipollicares, implexi, 
subflexuosi, laxe pinnati, pro more apice semel vel iteratim 
dichotomi ; rami inferiores breves simplices, rarius innovando- 
tioriferi. : 
* Ad fl. Bombonasa, in filicis fronde, Radule specimina prepauca legi, forsan 
ad R. tenellam G. Mex. Leverm. 149 referenda. . Pusilla viridissima fragilis. 
Folia haud recte complicata, lobo autem a plicwe apice plus minus divergente ; 
lobulo mammilla prealta conica instructo. Perianthia tenuia, ore crenata, 
longitudine varia. 
