722 



RECENT CHANGES IN THE FOREST-FLORA OF N.S.W, 



certain correlation between the beetle and the pine. There can be 

 little doubt that the spread of this beetle is dependent to some 

 extent on the prevailing climate. 



The mean rainfall in Sydney from 1840-1863 was about 48 

 inches, whilst that of the period from 1863-1880 was about 55 

 inches. The mean rainfall for the period 1880-1884 was only 

 about 40 inches. 



As sufficient observations have not been made in the interior, 

 we can only consider the Sydney x'esults ; and although it is 

 doubtful whether there is much similarity in the rainfall of 

 Sydney and the Interior, still it appears likely that a series of dry 

 years in Sydney indicates an isochrone drought in the interior. 



If we compare the observations mentioned above we shall arrive 

 at the following result : — 



It seems from this, that the drought is favourable to the spread 

 of the Diodoxus erythrurus and that this beetle then destroys the 

 pine, whilst the wet years prevent the development of this species, 

 which seems to attack the pine only, and enables the pine scrub 

 again to spread. 



This little contribution to the influence of climate on the flora 

 and fauna may perhaps hereafter be of use to scientists investi- 

 gating this most important subject. 



