HORN EXPEDITION-CRUSTACEA. 
229 
Most of the pools in the river-beds have very gradually-sloping sandy beds so 
that the water at the edge is very shallow. In this part the animals are always 
found floundering about with the carapace uppermost and making their way 
towards the margin. Here they immediately begin to scoop out a hole in the sand 
deep enough for the body to lie in and remain there as the water dries up making, 
apparently, no attempt to get back again into the deeper parts. This may possibly 
serve as a protection for the eggs which are thus covered by the carapace and 
preserved from drying up too quickly. With regard to the Decapocla secured 
Astacopsis bicarinatus is fairly common in the more permanent water-holes and 
evidently grows to a large size. It is much appreciated in common with a species 
of Unio as an article of food by the blacks. Whether it forms burrows and so 
can exist if the water-pool be dried up for some time is unknown but there is little 
doubt but that it can do so as this habit is adopted by the same species in other 
parts of Australia. 
In the case of Telphusa transversa, the freshwater crab, the banks of certain 
water-holes are riddled with its burrows; but it is probably more local in distribu¬ 
tion than the crayfish as we did not meet with it north of Charlotte Waters and 
it was especially abundant in one or two water-holes along the Adminga Creek. 
It will be seen that so far as their habits are concerned the Crustacea of the 
central district may be divided into two groups :— 
(1) . Those which can burrow and so tide over a certain length of dry season 
(Astacopsis, Tel[)husa). Both species included in this group have a very wide 
distribution over Australia. 
(2) . Those which require that their eggs shall be dried up prior to develop¬ 
ment (Apus, Estheria, Limnadopsis, Limnetis, Eulinmadia). These are naturally 
well adapted to such a district though none of the genera named are by any means 
confined to the Eremian region. 
Tlie most prevalent species Estheria packardi is widely distributed. Apus 
australiensis is known from Victoria, New South Wales and West Australia, 
whilst the species Limnadopsis squirei and L. tatei are so far as yet known confined 
to the central region the range of the former extending from Alice Springs in the 
north to Oodnadatta in the south. 
