HARDY. 145 



of the genus Stibosuma is somewhat doubtful and also omitted, together with 

 Diclisa. 



Summary. — Despite the fact that the distribution of genera is still imper- 

 fectly known, evidence that Australia has a strong zoological affinity with South 

 America is too prominent to be ignored. The 28.5 % of genera in common with 

 South America against the 5.7 % in common with Africa is too wide a difference 

 to be accounted for except by the theory that Australia and South America de- 

 rived a large part of its fauna from a common origin and it corroborates similar 

 evidence in other branches of Zoology. 



Further additions to our knowledge are required before any safe conclusions 

 can be drawn from the facts of the distribution and in the meantime it is hoped 

 that the tabulation given here will be found suggestive enough to stimulate further 

 enquiry. 



Mr. Charles Hedley in "The Palaeographical Relation of Antarctica" (Proc. 

 Lin. Soc. Lond., 1912, p. 80, reprinted in Smithsonian Inst it., 1913, p. 443) has 

 ably championed a theory that Australia has been connected to South America via 

 the Antarctic continent. If this could be proved and the geological period of 

 such connection determined, it would have a far reaching effect upon the study 

 of the. phylogeny of dipterous and other genera. 



[See Tables pages 146-7.] 



