HORN F.XPEDITION — SUMMARY. 179 



north-p.istoni Australia, for it has c\'i(lently spread nurtliwarils rathrr tlian soutli- 

 wards along the oast coast, and it may also be a,dded that the absence of Platypus 

 ill the north-cast is evidence against this route of migration, so that we are, in 

 reality, brought to the conclusion that the primitive marsupial, and possil)ly the 

 pi'imitive Monotreme fauna also, entered Australia from the south. 



The discoveries of recent years with regard to the extinct niarsupinl fauna 

 of South America together with the alliance between Australia and the latter 

 continent as shown by such form as Cystignathous frogs, certain birds and 

 amongst fishes by the Cyclostomata and Galaxias, etc., anrl Gundlachia amongst 

 Molluscs, point to a former land connection across Antai'ctic regions. 



Apart from the cpiestion of an ancient connection of Australia, with Asia- 

 there must have been two other connections existing ; 



(1) The first of those was, according to Mr. Wallace, with North-East 

 Australia itself and a land stretching southwards to the east of the continent and 

 now represented by various land-renniants — New Zealand, New Caledonia, Lord 

 Howe and Norfolk Islands — and accounting both foi- the presence of certain Austral- 

 ian types of plants in the New Zealand flora ai\d also as previously referred to for 

 the presence of Microphyura amongst Molluscs and Acanthodrilus amongst earth- 

 worms which are not found in tlu^ south-eastern parts of the continent, and 

 probably also for the distribution of sti-uthious liirds. Mr. Hedley, on the othei- 

 hand, is of opinion* that the element in the Australian fauna indicating affinity 

 with New Zealand is to be sought for in the connection of a similar land ai'ea 

 with an older Papuan land which was again united to the northeast of Australia. 



(2) The second connection was, according to the theory herein advocated, 

 between the south-eastern part of Australia, stretciiing across what is now 

 Tasmania, and allowed of the introduction of the early mammalian fauna by 

 way of a land connection with South America. 



At this time what is now Bass .Straits was dry land, allowing of communi- 

 cation with the south-castein part of the continent, whence animals could spread 

 northwards along the east coast and westwards into the central and southern parts 

 of the continent. The first of these connections probably took place after the 

 elevation of the Rolling Downs (Upper Cretaceous) sei'ies, and the second at a 

 somewhat later peiiod and at. a time when what is now New Zealand had lost the 

 connection with the southern antar('tic lands, by way of which it prob;d)ly 



* Nat. Science, 1S9:J, p. IST. 



12a 



