THE NAUTILUS. 65 
possible route’ for the migration from America to Australia of these 
Tertiary marsupials. But such a land could not have been con- 
nected with New Zealand, or the marsupials would have wandered 
there also. A great southward extension of Tertiary New Zealand, 
considered probable by Sir J. Hector,’ would, however, have availed 
to people the latter with much of the fauna and tora of the suppo- 
sitious Antarctic land, in the way that European plants are 
believed to have reached the Azores. 
This theory of the origin of Australian marsupials would also 
account for the discontinuous distribution of Gundlachia. 
The Australasian members of the genus known are G. petterdi 
Johnston, G. beddomei Petterd, MS.,and G. sp. undetermined, and 
probably new, from New Zealand. 
At present G. petterdi appears to be known, as adult, from only 
three localities: a small, shallow, stagnant pool near the First Basin, 
South Esk River, Launceston, Tasmania (Johnston and Petterd) ; 
a hill stream at Mt. Lofty, 8. A. (Tate), and a chain of shallow, 
stagnant ponds behind the sandhills at Henley Beach, near Ade- 
laide, S. A. (Adcock, Pulleine and Hedley). In this latter locality 
they were associated with Planorbis, Bulinus and Ancylus, the 
latter only determined by the shell. Their habit was to cling 
to drowned leaves and sticks, or to the submerged leaves and stems 
of water plants. So closely do they resemble Ancylus that a careful 
observer may, in the field, easily mistake one for another. 
The precise mode of the growth of the shell does not seem to have 
been related by any writer. Johnston says (Proc. Roy. Soc. Tas- 
2 Had the alternative route advocated (‘‘ Island Life,” 2nd ed. p. 497) by 
Wallace, “over what is now the Java Sea,” been used by the marsupials, then 
Timor and the South-Eastern Austro-Malayan Islands should, as Forbes log- 
ically remarks, have preserved some remnants of the migrants amid surround- 
ings so like Australia (Vol. iii, p. 22, Supplementary Papers, Royal Geo- 
graphical Society, 1893). Spencer has demonstrated (Rep. Aust. Assoc. Ady. 
Sci., 1892, p. 118) “that the diprotodonts had their origin in the Euronotian 
region,” which also seems to me, though not to him, to indicate the south 
rather than the north-west as the point of marsupial ingress into Australia. 
In his latest paper Prof. Zittel says (Geol. Mag., Nov, 1893, Vol. x, p. 512) : 
‘« For its [i.e., Australia’s] connection at one time with South America, the 
abundant occurrence of fossil marsupials in the Santa-Cruz beds of Patagonia 
is valid evidence.’’ See also Lydekker, ‘‘ Nature,’ May 5, 1892, Vol. xlvi, 
pp. L1-12. 
3 Address to the Geological Section of the Aust. Assoc. Ady. Sci., Adelaide, 
1893. 
