448 TRANSACTIONS OF SECTION E. 
the tropics. For example, the Podalyriee of Australia, South Africa, and the 
Northern Hemisphere are related to each other through Sophorer. The 
Eurasian types have been dispersed, during late geological time, to North 
America by way of North-eastern Asia, and thence along the high western 
plateaus to South America. 
Antiquity of Isolation of Australia—Great genera, such as Mimosa and 
Calliandra, are absent from Australia but are present in America, Africa, and 
Asia. The peculiar group of the Australian Podalyriez, comprising nineteen 
endemic genera and about four hundred species, also speaks eloquently of the 
long separation of Australia from Asia. The history of Acacia also may be 
summarised in this connection. The genus is divided into Gummitferm 
Vulgares, Filicine, Pulchelle, Botryocephale, and Phyllodinez. Species 700. 
The Gummiferez are the primitive type, and are well developed in America 
Africa, and Asia, only poorly represented in Australia and quite absent from 
Europe and New Zealand. They represent the xerophytic modification of a 
luxuriant Cretaceous plant, with bipinnate leaves, even at a time when the 
great continents were connected by way of the tropics. The Vulgares are the 
most important types, numerically, in extra-Australian areas, being abundant 
in America, Africa, and Asia. They are absent from Australia. The Filicinz 
belong to Tropical America. The Pulchelle and the Botryocephale are 
endemic in West and South-East Australia respectively. The Phyllodinex, with 
about 420 species, are Australian. Of these the Uninerves represent the earlier 
type, and are characteristic of poor, sandy soils. The home was Northern 
Australia. In the early stages the phyllode was narrow with the midrib form- 
ing the greater portion. The Pleurinerves appear to be modified Uninerves. 
Both types gradually pushed their way into the deserts, into West and South- 
east Australia, and into Tasmania. The Uninerves established themselves 
strongly in the cooler regions of the south, while the Pleurinerves, with the 
Juliflore, lagged behind and entrenched themselves securely in the tropics. 
Both during, and subsequently to, the formation of the great plateaus of Eastern 
Australia many peculiar phyllodineous types were developed, such as the 
Racemose and the Tetramere, and these, in part, during the later glacial period, 
moved northwards along the plateaus as far as South-eastern Queensland ; others 
again adapted themselves to subarid inland conditions. The endemic 
Botryocephale, also, are in the main a response to plateau development in 
South-east Australia. during later and post-Tertiary time. The western 
alluvial plains of Eastern Australia, formed during late and post-Tertiary time, 
gave rise to groups of the Pleurinerves, such as the Microneure. 
In conclusion, Australia has been isolated from Asia for a great period, 
and the Leguminose of the fertile tropics of the island continent are not com- 
paratively recent and derivative, as has been stated, but are examples of types 
once cosmopolitan, whose development has long been arrested while the great 
majority of the endemic types are younger and vigorous xerophytes induced by 
the altered geographical conditions. 
2. Eastern Australian Topography and its Effect on the Native Flora. 
By R. H. Campace, F.L.S., &c., Chief Mining Surveyor, New 
South Wales. 
The chain of mountains known as the Great Dividing Range extends through- 
out the length of Eastern Australia at distances varying from about twenty 
to nearly three hundred miles from the coast-line. It consists of an uplifted 
dissected plateau ranging from about 1,500 to 7,300 feet above sea level, the 
generally lower portions being in Queensland, and the higher in southern New 
South Wales and Victoria. In general the eastern face is fairly steep and 
high, and exercises more influence in differentiating the humid climate of the 
east from the drier climate of the west, than does the actual water-parting itself, 
which is often only a slight ridge in various positions on the plateau. The effect 
of the mountains in the south is to create three climates, a humid and dry one 
on the east and west sides respectively, and a cold one on the summit which 
acts as a barrier between two floras which would otherwise commingle to some 
extent at lower levels, 
