24- 
REVISION OF THE GENUS EUASTACUS 
ture of the carapace and abdomen, and by the form of the 
rostrum, squame and great chelae. 
E. hispinosus is the species that is fully figured, with its 
complete life history, in the paper under the title “The Life 
History of the Gippsland Crayfish,” Australian Museum 
Mag., April- June, 1937, p. 186. 
HTkSTRIBUTION. 
During the progress of the foregoing revision sketch maps 
(Plates viii and ix) were prepared to illustrate the known 
distribution of the genus Euastacus, but in connection with 
three species (eJongatus, arniatus and yarraensis) , the distri- 
bution as shown thereon does not conform with the present 
river system ; their distribution is made intelligible, however, 
if we accept Professor Gregory’s theories (37) of the devel- 
opment of the Victorian river system which are supported 
by the work of Fenner (36), Jutson (39, 40) and others. 
Gregory’s theories are not accepted by certain authors, e.g. 
Hills (38) and Edwards (35). 
Since crayfishes of the genus Euastacus inhabit rivers and 
creeks, seldom leaving the water to wander for considerable 
distances on land as is done by members of allied genera, their 
distribution is more or less dependent upon the river system. 
As mentioned in a previous page, the Murray River contains 
two distinct species E. elongatus, sp. nov., and E. armatus 
(von Martens). E. armatus occurs in two sections of the 
Murray, one from its source to Cobram and the other from 
west of Swan Hill to the mouth of the river ; and also in the 
rivers connecting with these sections both in New South 
Wales and Victoria. E. elongatus inhabits the section of 
the Murray River between the Broken River and Swan Hill 
and also the rivers flowing into this section of the Murray. 
Strange as this demarcation seems at first sight, it is 
correlated with the findings in other branches of science. 
Mr. A. S. Kenyon, former Chairman of the State Rivers 
and W ater Supply Commission, has kindly supplied me with 
his notes on the River Murray system (see Appendix). He 
considers that in times of flood the sections of the Murray in 
which armatus occurs, together with the Edward, form the 
Murray proper and that the section where elongatus is found 
may be considered an extension of the Goulburn. This theory 
of the distribution of the flood waters supplies one reason for 
the curious distribution of the two species in the Murray. 
E. elongatus, as already mentioned, is found in tributaries 
