101 



On sending specimens of the two ferns to the Assistant 

 Ourator of the Melbourne Botanic Gardens, Mr. F. Pitcher, 

 lie writes confirming my identification of the one as Pferis 

 tremida, R. Br. ; the other he determines, on reference to 

 their Herbarium, as Aspidium loiitum, var. projjinqintm, F. 

 M. Bailey, and comments on it as follows: — "The other 

 specimen appears to be that of Aspidium unitum, var. 

 propinquum, F. M. By. It is much more deeply lobed and 

 lias more acute dentations than is the case in A . molle. It 

 corresponds to our specimen under that name, although, as 

 far as I can ascertain, .4. unitum, is only recorded from Wes- 

 tern Australia, New South Wales, Queensland, and North 

 Australia. The variety propinquum was so named by F. M. 

 Bailey, and is found in Queensland." 



Peculiar Conditions. 

 The circumstances under which these two ferns occur are 

 very remarkable. The climatic conditions which obtain at 

 the locality (20 miles above Mannum) are of the dry arid 

 character common to districts with a similar low rainfall. 

 The two conditions that make it possible for these two ferns 

 (whose true habitat is in a moist and more or less continuously 

 wet climate) to live in such a locality are moisture derived 

 by capillary attraction from the river and the aspect, shaded 

 as it is during the greater part of the ,day from the sun's 

 rays. It is just possible that the evaporation of the water 

 of the river may give a moisture to the atmosphere immedi- 

 ately surrounding the ferns, and thus, to some extent, miti- 

 gate the effects of the dry, scorching winds so common in 

 that locality. 



Origin. 



There are only two possible hypotheses, as far as I can 

 see, to account for their occurrence in this locality. Either 

 they are survivals, the sole remaining representatives of the 

 time when the Murray Valley was blest with an abundant 

 rainfall, or the spores of these ferns were carried by the 

 agency of the river and retained their vitality throughout 

 their long journey from the mountains where the River Mur- 

 ray, or the River Darling, has its source in far-off New South 

 Wales or Queensland. 



The identification of one of the specimens with a variety 

 that has only been recorded from Queensland throws con- 

 siderable light on the subject, and suggests that the source 

 from which the spores originally came was in the mountains 

 of Queensland, where the river Barwon, or other tributary 

 of the Darling, has its rise. If this surmise is correct the 

 spores must have travelled some 2,200 miles. 



