48 A CONTRIBUTION TO, ETC. 



isli brown or tawny colour, somewhat rough to the touch. The 

 other species found in this part of the colony, as well as in many 

 localities near the eastern coast, differs principally from the pre- 

 ceding in having a more slender caudex, very dark-coloured 

 rachis, and segments of fronds serrulate in the upper part. It 

 has been doubted whether this is specifically distinct from A. 

 " Australia } but persons who have closely examined both plants in a 

 living state, regard them as distinct in habit and appearance, al- 

 though it is said that, in some of the younger plants, it is exceed- 

 ingly difficult to determine whether they differ from A. Australia 

 or not. This species used to be marked A. ctffinis, but when Sir 

 William Macarthur took home som'e living plants for the garden 

 at Kew, Sir "W. Hooker named the species A. Macartkuri, in 

 honour of that distinguished colonist who has laboured for so 

 many years to develop the natural resources of the colony, and 

 to make them known not only in England, but on the continent 

 of Europe. In addition to these, a third AlsopJiila has received 

 the name of A. Cooperi, from Sir Daniel Cooper, formerly 

 Speaker of our Legislative Assembly ; and my learned friend Dr. 

 F. Mueller, has recently described two new species from Rock- 

 ingham Bay (A. Rebecca and A Robertsiana) , which, though 

 much smaller than those previously noticed, are characterised as 

 tree-ferns of remarkable beauty, and well worthy of cultivation- 

 The largest of the genus in this part of the world is A. excelsa, of 

 Norfolk Island, which sometimes attains the height of eighty 

 feet. Whether this is really distinct from some of our species, 

 remains yet to be proved. Dr. F. Mueller seems to think that 

 it is not, as it differs from A. Australia only in the chaffy scales 

 of the rachis ; whilst in the indentations on the caudex, occas- 

 ioned by the annual falling off of the fronds, it is said to resemble 

 A. Cooperi. 



The next genus of the sub-order is Dickaowa, w r hich derives its 

 name from the late Mr. James Dickson, a celebrated British cryp- 

 togamic botanist. The sori of this genus are situated at the 

 margin of the frond, and always at the apex of a vein. It differs 

 also from AlsopJiila in having an indusium, or rather a two-fold 

 one, formed in part of a more or less changed lobule of the frond, 

 and in part of a more or less united indusium, generally re-curved, 

 two-valved, or entire. The most remarkable species in Australia 



