CHARACTERS OF TRIBES AND GENERA. 167 
by A. acrostichoides and A, Stelleri, all of which are in the 
* Species Filicum” considered as representing one species 
only. Many other species have been added from time to 
time to this genus, but, on account of their having a spe- 
cially well-defined indusium, are now most of them referred 
to the genera Cheilanthes and Pellea, several of which, such 
as Belleg marginata and P. angustifolia, have a strong 
claim in habit to be associated with Allosorus. Their 
special indusium however marks them as being distinct, the 
terminal oblong sori of Allosorus indicates its relationship 
to be with Gymnogramma. 
Sp. A. crispus, Bernh. (v v.); A. Brunoniana, Wall.; 
A. acrostichoides, R. Br.; A.Stelleri, Rupr. (Pteris gracilis, 
Michz.); A. glauca, Cav. (Pellea hirsuta, Hook. Syn. Fil.). 
Ons.—The last two species are placed under Pellea in 
the “Synopsis Filicum.” See observation under Pellea 
for my reason for placing them here. 
77.—Jawxsoxra, Hook. and Grev. (1831). 
' Hook. Sp. Fil. 
Vernation sarmentose, slender, elongating, naked, sub- 
hypogeous. Fronds short stipate, distant, linear, pinnate, 
erect, 1 to 14 foot long, rigid, densely covered with tomen- 
tose articulate hairs when young; pinne numerous 
subrotund, À to } inch long, coriaceous, short petiolate, 
generally deflexed, contiguous and  imbricate, margin 
revolute, induseform. Veins flabellately forked. Sporangia 
occupying the lower part of the venules, forming short 
sori, which become confluent into one central sorus,covered ` ` 
with crinoid jointed hairs, and partially hid by the induse- ` 
form margin. ae 
Type. Pteris imbricata, Cav. 
