PROCEEDINGS OF SECTION 0. 199 



gives a good indication of the composition of the Australite. My present 

 impression is that the less acid forms are concentrated along the borders 

 of the belt and that the acid ones are commoner along the central line 

 running from Melbourne towards the Lake Eyre District. It is to be 

 hoped that careful specific gravity determinations will be made and 

 recorded, so that this point may be proved or disproved. This question 

 of provincial distribution is of vital importance, as the establishment 

 of such a distribution would go a long way towards proving that the 

 Australites were of meteoritic origin. This distribution is easily con- 

 ceivable on the meteoritic hypothesis, but seems quite impossible of 

 explanation by any other existing hypothesis. 



The conclusion we arrive at then is that since all other hypotheses 

 fail to fully account for the source, form, composition, and distribution of 

 A-ustralites, whereas the meteoritic hypothesis seems to be capable of 

 80 doing, the balance of evidence is distinctly in favour of a meteoritic 

 origin being ascribed to these interesting bodies. 



Summary. 



Two new analyses of Australites are recorded, and it is shown by 

 means of the Quantitative Classification that they in common with 

 Molda\'ites, Billitonites, and other Australites are abnormal in compo- 

 sition. 



By the use of variation curves it is demonstrated that the Austra- 

 lites are genetically related, and that they show a community of origin 

 with the Billitonites and Moldavites. 



The forms of Australites are discussed and arguments are advanced 

 in opposition to Mr. Dunn's hypothesis and in favour of their forms 

 being impressed on them by rotation while in a fluid state. 



It is pointed out that the upholders of the volcanic origin of Aus- 

 tralites have so far been unable to point to any volcano in or near 

 Australia which has produced lava at all comparable with Australites 

 in composition. 



Any hypothesis to be accepted must be capable of explaining the 

 source, composition, form, and distribution of Australites. It is 

 shown that other hypotheses fail to do so, and by a process of elimination 

 we are reduced to the conclusion that the only tenable hypothesis is 

 that Australites as well as Billitonites and Moldavites are of meteoiitio 

 origin. 



DESCRIPTION OF PLATE VII. 



Vir'aMon Diagram of Au? ralitef, Billitonites, and Moldavites, constructed 

 irith silica, p8r.38 itages as abjcissje and parcantages of other oxides as ordinates. 



