698 BOTANY OF THE INTERIOR OF NEW SOUTH WALES, 



soon fall. Some, however, when attached to light substances of 

 a suitable shape to be easily blown about, may get carried away 

 in an upper current after being raised by the whirlwind. Many 

 of the prevailing high winds in the interior come from a direction 

 approximating the north-west, reaching the coast in the summer 

 as hot winds; and besides the amount of matter raised by those 

 winds alone, they are undoubtedly fed in a small wa}^ b}^ whirl- 

 winds. A careful study of the distribution of several species 

 between the Bogan and Lachlan will show that the spread has 

 been towards the south-east. Two species in particular may 

 be mentioned as having travelled in this way, viz., Acacia 

 aneura (Mulga) and A. excelsa (Ironw^ood) ( Vide Part iv,, p. 321). 

 It is possible that there are small clumps of Brigalow nearer 

 to Marsden than Nyngan. It may perhaps extend south- 

 ward from Cobar, but if so, I am satisfied from the result of 

 numerous enquiries made that it is rare. In fact it is scarce any- 

 where south of the Great Western Railway. I could find neither 

 flowers nor pods the first week in September, and it is curious 

 that various collectors have from time to time exjoerienced a 

 difficulty in getting complete specimens. When the species was 

 first described the pod was said to be unknown, and this part of 

 the description was only supplied by Messrs. Maiden and Betche 

 in 1899 (these Proceedings, 1899, Part iv.), although pods had 

 been collected prior to this later date. 



Another instance of this isolation was once noticed in the case 

 of a Eucalypt which was not even supported by seedlings. In 

 the year 1890 my assistant drew m}^ attention to a tree growing 

 about 10 miles west of the road from Young to Grenfell, at a 

 point about midway between these two places. Mr. Quinn, the 

 owner of the land upon which the tree grew, stated that it was 

 the only one of its kind which he had ever seen, never having 

 been in the interior, but a Western man had told him it was a 

 Mallee and that no others were to be found within 50 miles of it. 

 In 1892 I visited Cobar, and at once recognised one of the Cobar 

 Mallees as being similar to the solitary tree near Grenfell. As 

 I did not collect specimens from the Grenfell tree, I cannot speak 



