AUSTRALIAN FERNS. 63 



New Zealand, Tasmania, Victoria (Dr. I\ Mueller), Northern 

 India, Mexico, and very recently in the vicinity of Mittagong. 

 Dr. Brown considered the form A. laxum as a separate species, 

 as he had never seen it proliferous ; but Hooker unites not only 

 that variety but also several others, with A. bulbiferum, as he 

 does not regard the proliferous pinnae as indicating specific dif- 

 ference. Dr. Hooker thought that this species was very closely 

 allied to A.flaccidum {A. odontites, E. Brown), and that it some- 

 times passes into A. Hookerianum, but Sir William expresses a 

 different opinion. A. obtusatwn and A. difforme, which Brown 

 regarded as distinct, are now placed together, as they " exhibit 

 almost a gradual transition from the one to the other." Some 

 specimens which Mr. Macgillivray forwarded to me from Cla- 

 rence River confirm this view, for the pinnae vary considerably in 

 shape and appearance. In addition to the species of Aspleniutn 

 enumerated, I may mention A. simplicifrons (Fragmenta, vol. 5, 

 p, 74) from Eockingham Bay, which has recently been described 

 by Dr. Mueller, and also A. polypodioides, A.cuneatum^and.A. 

 sylvaticum, which have been determined by the same indefatigable 

 author to be identical with the Indian species. Perhaps on the 

 whole, this genus is the most interesting in Australia, not merely 

 on account of the numerous species, but for the great dis- 

 similarity of the fronds. It will appear, however, that the 

 species are very limited in the neighbourhood of Sydney, only 

 two being found there, and those so different in their form and 

 character, that the casual observer would never suppose them to 

 be allied. With regard to the species themselves, there is some 

 obscurity, for the most distinguished botanists are by no means 

 agreed as to what are true species and what are mere varieties. 

 As an instance of this, it may be seen that Hooker regards A. 

 bulbiferum as perfectly distinct from A. flaccidwn, whilst Dr. F. 

 Mueller assures us, that " in the fern-tree ravines of Victoria, he 

 had frequent occasion to trace A. bulbiferum and A. flaecidwm 

 into each other," both being varieties of A. marinum. And pro- 

 bably this latter opinion is correct, and it affords another illus- 

 tration of the advantage of studying plants as they grow in 

 various localities, and are influenced by surrounding circum- 

 stances. But, after all, we must bear in mind the philosophic 

 caution of Berkeley, " that in these matters we are not to look 



