72 A CONTRIBUTION TO, ETC. 



by curved or transverse veins ; but Hooker, not regarding this 

 character as sufficient for generic distinction, includes the so- 

 called genus amongst the species of Polyp odium. Dr. Mueller's 

 discovery will, doubtless, prove interesting, as the allied species 

 are principally American and West Indian plants. The species 

 next in order are by some authors referred to Niphololus, on ac- 

 count of the stellated hairs or tomentum with which the fronds 

 are clothed on the under surface ; but this character is too arti- 

 ficial to render such a division necessary, and therefore P. an- 

 gustatum, P. acrosticlioides, P. rupestre, and P. conjluens, are re- 

 tained as species of Polypodium. The first two of these occur 

 principally in the north-eastern paVt of this continent, and the 

 second is remarkable for having the longest and narrowest fronds, 

 in proportion to their length, of any of the group, some being 

 three feet long. There is some difficulty respecting P. rupestre 

 and P. confluens, and probably they are mere varieties of one 

 species, although in the diposition of the sori and the size of the 

 fronds they seem distinct. The first form is very common on 

 moist shady rocks in creeks, and is widely distributed in Eastern 

 Australia. It has fronds of two shapes, the sterile one being 

 obovate or roundish, and the fertile, linear-lanceolate, gradually 

 tapering into the stalk. In the barren fronds, the veins unite in 

 a net-like manner, but somewhat irregular, whilst some of the 

 veinlets are free in the areoles. As the fronds become elongated 

 and fertile, a midrib is partially developed, and the areoles in- 

 crease in length. The venation resembles that of P. Billardieri, 

 but it is sunk in the frond, and scarcely perceptible in a dried 

 specimen. The fronds which I have collected seldom exceed 

 three or four inches in length, and not a quarter of an inch in 

 width, whilst the fructification is very copious and closely packed 

 together on the upper half of the frond. In the variety of this 

 fern which occurs plentifully on Ash Island, and for specimens of 

 which I am indebted to the kindness of Miss Scott, the fertile 

 fronds are sometimes more than a foot in length, and half an inch 

 in width, being more glabrous than the preceding, and having the 

 fructification confluent near the apex. Before I had read Sir 

 "William Hooker's descriptions of these ferns, I thought that the 

 Ash Island variety was Brown's P. conjluens, for many of the 

 specimens procured by that illustrious author came from Hunter's 



