REVISION OF THE GENUS EUASTACUS 27 
coastwise rivers of that State as far north as Sydney. In 
Victoria it also inhabits the headwaters of the Yarra River 
and its tributaries above Warburton, but so far only small 
specimens averaging six inches in length from rostrum to 
telson have been received from this area. 
North of the Main Divide it inhabits the Stevenson River 
aiid the headwaters of the Yea. On the map (Plate IX) the 
Stevenson River is indicated but is not named. In rises on Mt. 
Orant and flows past Marysville to join the Taggerty, the 
combined rivers then joining the Acheron at Buxton. Small 
specimens have been taken at Gordon’s Bridge on the Yea 
River, but comparatively large specimens have been taken 
from the Stevenson — one male measured inches from ros- 
trum to telson. 
In setting out the above facts regarding the distribution 
of the four species, no attempt is made to assert that they are 
proof of any of the theories mentioned, but the evidence 
obtained regarding the rivers which at some previous time 
must have been connected since the genus Euastaciis is 
dependent upon the river system for its dispersal, has been 
put forward so that it may be of some assistance to future 
workers both on the distribution of the Australian crayfishes 
and on the development of Victorian physiography. As has 
been mentioned previously consideration of the theories is 
the only way in which the otherwise anomalous distribution 
of the genus can be explained. 
APPENDIX. 
The following paragraphs, which have a bearing on the 
distribution of E. elongatm and E. armatus, are taken from 
Mr. A. S. Kenyon’s unpublished notes on the Murray River 
system : — 
The Murray River, though generally looked upon as one and the same 
river throughout its course, is truly so only in times of low and moderate 
flow. Taking its rise in the Australian Alps, it flows in a normal manner 
along its valley to the foothills, rolling along its bed vast masses of boulders, 
shingle and gravel. Emerging upon the old lacustrine plains at Corowa 
and Yarrawonga, it leaves the stones and gravel behind, carrying onward 
only the sand resulting from their grinding higher up, with the silts and 
clays in suspension derived from the erosion of its banks and from the 
land slides, in wet seasons, on the steep sides of the mountain valleys. 
Shortly after it enters the plains and receives the waters of the Ovens 
River, the Murray begins, definitely at Cobram and Tocumwal to assume a 
deltaic character; and in flood times completely loses its identity in what 
can best be named and described as the Moira Marshes. 
Into the Moira Marshes also pour the floods of the Goulburn River. From 
