THE FERN WORLD OF AUSTRALIA. 
35 
distinct series close to costnla. Found most abundant in Queens- 
land in the Maroochie scrubs, but also met with in many parts 
of N. S. Wales. 
A. RolDertsiana, F. v. M. Trunk six to eight feet high, not 
thick. Fronds bi-pinnate, the rhachis both general and partial as 
well as the pinnules and sori hispid or sprinkled with rigid hairs. 
Secondary pinn£e two to three inches long. Pinnules distinct, four 
to six lines long, deeply pinnatiiid, the upper ones of each pinna3 
smaller more entire and confluent. Sori rather large, solitary 
opposite each lobe of the pinnule. Found in the deep close 
gullies of the Ranges, Rockingham Bay, Queensland. 
Tribe VI. Polypodieje. — Habit various. Spore-cases small, 
with a longitudinal or scarcely oblique ring, usually bursting on one 
side in the shape of little helmets, numerous and stipitate in sori 
or patches on the under side or rarely on the margins of the fronds, 
with or without an indusium. 
A Sori covered at least when young with an indusium. 
XYII. — DiCKsoNiA, L'Heritier. 
Trunk arborescent, or a creeping rhizome. Fronds large, com- 
pound. Pinnules penniveined. Sori terminating veins close to 
the margins of the frond. Indusium either globular and two- 
valved or cup-shaped and entire, the upper valve or upper part of 
the cup adnate to the frond, and continuous with the margin. Name 
in honor of Mr. James Dickson, a Scotch botanist. 
D. antarctioa, Labill. Woolly-tree fern. Trunk or caudex 
said to attain thirty to fifty feet in height with a diameter of 
four feet at the base, always much stouter in the stem than the 
other Australian tree ferns. Fronds six to twelve feet long, bi- 
tripinnate,,,the stipes and rhachis scabrous or smooth, covered with 
soft hair in a young state. Secondary pinnaa two to three inches 
long. Pinnules or segments distinct or tlie upper ones confluent, 
nearly flat and acutely toothed when barren, thicker and obtusely 
lobed when fertile. Sori solitary on each lobe. Indusium globular, 
about half line diameter two-valved, the upper valve adnate to the 
lobe of the frond and undistinguishable from it except near the base 
where there is on each side a narrow free margin. Only met with 
in quite the southern parts of Queensland, but generally through- 
out N. S. Wales, Victoria and Tasmania, as also in a few parts of 
South Australia. 
D. YoTingise, C. Moore. Trunk ten to twelve feet high, marked 
by scars showing the junction of the former fronds with the caudex. 
Fronds more coriaceous and glossy than in D. antarctica. Stipes 
clothed with rather long glossy brown hair ; rhachis fen-uginous- 
pubescent or glabrous, not scabrous. Secondary pinnae two to three 
inches long. Pinnules three to six lines long when fertile, deeply 
divided into rounded lobes like those of the last species but larger. 
Indusium one line diameter, the upper valve entirely adnate. 
