SUNKLANDS OF PORT PHILLIP BAY AND BASS STRAIT 113 
wallabies, rat-kangaroos, ground birds, etc. The wombats live 
on grass, the bark of certain trees and shrubs, particularly 
eucalypts, native cherry and sword grass, and fungi. The echidna 
or spiny ant-eater is found in rocky country in open forest or 
scrub. The living species of Zaglossus found fossil in Tasmania 
are now restricted to New Guinea. 
The platypus is aquatic, and is found along most rivers in 
eastern Australia on both sides of the Dividing Range as well as 
in many rivers and lakes in Tasmania and the streams of King 
Island. It collects its food under water — small aquatic insects, 
worms, Crustacea, etc — on the river or lake beds. 
The remains of the food of Diprotodon found with its skeleton 
at Lake Callabonna, South Australia, consisted of small twigs and 
stems, but this may have been a starvation diet — the only food 
available in a region that had become arid (Stirling 1900). 
Pleistocpine Land Bridges 
The Yolandean land surface that joined the mainland with 
Tasmania in the Yolande or Riss Pleistocene stage was, during 
the previous interglacial stages, beyond the reach of the custatic 
rises of sea level : it was not until tectonic subsidence brought it 
within range in the subsequent interglacial stages that it was 
flooded. Along the eastern and western sides of this land surface, 
a short distance inland from the shores of the Tasman Sea and 
Southern Ocean, were two erogenic ridges trending S.S.W. The 
only remnants of the ridge on the east — the so-called Bassian 
Isthmus — are the islands between Wilson’s Promontory in 
Victoria and Cape Portland in Tasmania, including the Furncaux 
and Kent Groups ; that on the west extended from the Mornington 
Peninsula in Victoria to Cape Grim, the north-west extremity 
of Tasmania, and passed through King Island and the Hunter 
Group. Between these two ridges was the wide, mature valley 
of the middle reaches of the Tamar Major River, and between 
the King Island ridge and the Otway Peninsula were its lower 
reaches and estuary — the lowest part of the Bass Strait Sunkland. 
The surface of the Tamar Major River basin was one of low 
relief. The physiognomy of its vegetation inferred from the 
ecology of the living and fossil faunas of both the islands of Bass 
Strait and Tasmania, on the assumption that they migrated from 
the mainland, was that of an open forest and a forest with strata 
of from taller to dwarf shrubs, herbs, and grass land. The food 
of the animals indicates the jjresence of insects, reptiles, birds, 
ants, land shells, fungi, etc., and of earthworms, implying the 
