539 



On the Ecology of the Ooldea District. 



By R. S. Adamson, M.A., B.Sc, and T. G. B. Osborn, D.Sc. 



[Read October 19, 1922.] 



Plates XXXII. to XXXVI. 



Comparatively little has been written about the ecology 

 of the arid regions of Australia, though these form a large 

 portion of the continent. In South Australia, which has an 

 area roughly three times the size of the British Isles, five- 

 sixths of the total area has under 10 in. of rain per annum. 

 A vast field, therefore, is awaiting examination. One reason 

 that hsLS contributed to the neglect of this work is the difli- 

 culty of visiting the places and the time occupied in the 

 journey. The recent opening of the Transcontinental (East- 

 West) Railway connecting South and Western Australia has 

 made very accessible an area that until the last few years was 

 visited by but few white people. The Ooldea district lies well 

 within this area, and offers scope for examining the arid flora, 

 the more so that, owing to an abrupt change in the type of 

 soil in the immediate locality two distinct habitats are avail- 

 able. Cannon visited Ooldea recently in connection with his 

 work on the Arid Flora of South Australia, but his account 

 was brief, and no attempt was made by him to deal with the 

 flora as a whole. 



Ooldea is a station on the Transcontinental (East -West) 

 Railway, 427 miles west of Port Augusta and 374 ft. above 

 sea level. The Ooldea district is one of great biological 

 interest because of its situation on the eastern boundary of the 

 Nullarbor Plain, at the point at which the railway line leaves 

 the sandhills and runs over the limestone plains. In August 

 of this year we made a stay of six days in the district, and as 

 a result of this visit the following account of the vegetation 

 is given. It is a pleasure to express our thanks to the Pre- 

 sident and membersi of the Ooldea Progress Association for 

 the facilities they placed at our disposal ; to Mr. T. Davison, 

 engineer at the ''Soak," for his guidance in that area; and 

 to Mr. A. G- Bolam, stationmaster at Ooldea, for meteor- 

 ological data and help in various ways. We are also indebted 

 to Mr. J. M. Black, who has determined some of our material 

 for us. Mr. J. H. Maiden, F.R.S., has kindly named the 

 Eucalypts. 

 q2 



