44 
The South AustraUan Naturalist. 
XOTKS ON AX AUSTRAJAAX FRESH-WATER CRAB. 
By Herbert M. Hale. 
Duriiiii' a visit to Central Australia in August, 1924, Prof, 
Wood Jones collected living specimens of a fresh-water oral) 
(Geothelphusa transversa). The crabs were at this time aestiva- 
ting at the bottoms of burrenvs, two feet or less in depth, in the 
tlry bed of the PAnniss Creek. They were brought to Adelaide, 
and some of them have been maintained in aquaria for the last 
ten months. 'Fwo pairs were given to the Mwiter, and these were 
at once installed in an observation vessel containing a mass of 
sand mixed with gravel, arranged in a gradual slope with the lower 
end leading into a small pool of water. Raw beef is supplied as 
lood, and this is readily eaten. 
Tor two or three days after being introduced into their neii 
surroundings the crabs remained in the water, at rlie side o' 
the aquarium nearest to a window, but later they ascended the 
damp sandy slope and excavated vertical or slightly oblique bur- 
rows. The pair of large, curved chelae are used for digging, the 
sand being scraped together in a roughly spherical mass. As 
each little heap is compacted it is lifted with the fore-limbs ami 
deposited at the mouth of the burrow; the masses are arraneed 
around the entrance so as to form a low chlmnev or crater, the 
interior of which is smoothed by the crustacean with the outside 
of the clielae. d’he finger and thumb action of the chelae is used 
in feeding but not in excavating. 
It has been mentioned that pebbles were placed in the sand 
in the aquarium, and naturally the crabs occasionally met with 
these as their shafts deepened. If small enough to be manipula- 
ted, a stone was carried up the burrow and deposited at the mouth, 
but if a large pebble were encountered, the burrow was continued 
;!t an angle so as to avoid the obstruction. One crab, which was 
excavating an oblique shaft, experienced dilFculty in persuading 
a pebble to sit at the entrance; after the stone I'.ad once or twice 
rolled down the hole again, the crab held it in position by resting 
one chellpcd against it, and pushed sand beneath it with the other 
chelae. Ttxcepting in the case of a specimen v'hich had lost a 
cheliped, each individual excavated a separate burrow; the damag- 
ed individual afterwards shared the burrow of one of the others. 
In March of this year two of the crabs — a male and a female 
— moulted, and are now slightly larger than when received; at 
this time the other pair died. 
