732 PROCEEDINGS OF SECTION F. - 
easily to be understood when one considers the annual voyages by 
these people down the Cape York coast on the one side and 
across Torres Straits on the other, and that on these voyages 
they obtain wives from the Australian mainland and the New 
Guinea Islands. 
Tam therefore led to believe that the Australian ancestors 
must, equally with the Tasmanians, be held to have reached this 
continent by some land connection, or, at least, a land connection 
so nearly complete that the breaks in it might be crossed in 
vessels no better than the bark canoe of the present time. 
If these conclusions are well founded there arise certain 
questions which demand answers. What evidence is there of a 
former land conneetion between Australia and other lands to 
the north or north-west, and between Australia and Tasmania 
within the limit of time fixed by the probable existence of man ? 
A reply to these questions can only be given by the sciences of 
physical geography and geology, and the time limit restricts the 
inquiry to those later Tertiary or Post-Tertiary lands from whence 
such migrations might have proceeded. 
Thus their direction is indicated as having been probably from 
the north or north-west of Australia. 
Dr. Wallace, in his classical work on the Malay Archipelago,* 
directed attention to several matters bearing upon this question, 
which still remain as significant as when he wrote them in 1869. 
A deep but narrow sea channel, being part of what is now 
known .as ‘“ Wallace’s Line,” separates areas of shallow seas 
bordered by great ocean depths,+ while the boundaries of the 
shallow seas indicate the former extension on the one side of the 
Austral and on the other of the Asiatic continent. 
The chain of islands which extends from the Malay Peninsula 
towards Australia, ending with Timor, when considered in con- 
nection with the boundaries of the shallow sea, represents a former - 
continental extension, probably only broken by the channel 
between Bali and Lembok,{ and a channel between Timor and 
Australia, 20 miles in width§ The former, which is onl 
15 miles wide, has sufficed to stop the advance of the larger 
mammals from the Asiatic to the Austral region, and the latter 
strait has similarly prevented the Australian mammals from 
entering Timor. 
If this was the line of migration of the early Tasmanians and 
Australians, we should have to assume either that they were able 
to cross the deep sea straits on rafts or in bark canoes, or that 
those sea straits were at such a comparatively recent geological 
time much narrower than the soundings suggest. 
* LYMM. ARG. { Lvl. § LVI, p. 823. 
