IIOUN EXPKDITION^SUMMARV. 151 



species found uutside tlie area. The fi-esh water molluscaii fauna lias been 

 increased from one to thirteen species. 



Speaking of the land niolkisca Professor Tate says, " Tlie facies of the fauna 

 appro.xiaiates more to that of sul)-tropical and tempcn'ate West Australia tli;in of 

 any other part of the continent, and is in strong conti-ast with tlie highly 

 diflerciitiated fauna of tropical and sub-tropical Queensland, situated to the east of 

 the Cordilleras, to which it is geogrnphically equally near. The limited number of 

 genera represented, together with the facts of their geographic distribution, would 

 seem to indicate a primitive population, which has been maintained in an isolated 

 condition by climatic and geologic changes." 



Of the species described T/wrsifes fodinalis is recorded from West Australia 

 and the interior of New South Wales, T. pcriiijlata from West and South 

 Australia, Alicropliyiini liciit'ulaiisa from North Queensland and the Northern 

 Territory, Pupa coiitraria from West Australia, Siucinea interioris from the 

 interior of Queensland. 



Taken as a whole the distribution accords well with that of other groups such 

 as the Marsupials ; the main allinity lies with West Australia, whilst T. fodiita/i'^, 

 T. periiijlata^ and S. interioris, show athnity with the interior part of the continent 

 lying to the east. There is the same striking contrast between the molluscan 

 fauna of the Centre and that of Northern and Tropical Queensland on the one 

 hand and the south-eastern coastal districts, including Tasmania, on the other, 

 which in reality is the leading feature of the whole central fauna. 



At the present time there can be no passage of land Molluscs either into or 

 out of the Central region, which has been in this respect i-solated since Pliocene 

 times. To account for the relationships of the land Mollusca we must postulate 

 what there is abundant evidence of — a more favourable climate in Pliocene and 

 earlier times allowing of migration from the west, north and to a lesser extent the 

 east, both into and out of the Central area. 



Whilst the Rolling Downs formation (Upper Cretaceous) was being deposited 

 the Central highlands formed a large island mass. Professor Tate says : "At this 

 period a more or less cosmopolitan fauna and ilora prevailed, and it was doubtlessly 

 then that the Larapintine area acquired its species of Microphyura, Charopa and 

 Flammulina and those species of a more or less maritime habitat belonging to 

 Liparus, Stenogyra, Pupa and Succinea. How else is it possible to account 

 for the presence of about eight species of land snails in the very centre of the 

 continent absolutely isolated from allictl or identical species which are to-day cir- 



