14 NATURAL SCIENCE [July 



Westralian Water-supply 

 One of the difficulties in the Ooolgardie and Kalgoorlie Goldtields is 

 the absence of water. The success that has attended the sinking of 

 Artesian wells in the sister colonies, notably in Queensland, to 

 which we have often referred, suggested that similar action might 

 be taken with profit in Western Australia. Mr A. Gibb Maitland, 

 however, the Government Geologist, in a report that he has just 

 sent us, comes to most pessimistic conclusions. The Ooolgardie 

 country consists for the most part of granitic rocks ; which are 

 weathered on the surface so as to form a superficial water-bearing 

 layer of no great depth* but yielding enough water for ordinary 

 purposes in certain spots ; this water, however, is usually brackish. 

 Below this weathered zone, however, none of the rocks are suffici- 

 ently porous to allow of the absorption and transmission of water ; 

 and since they are likely to be still more compact at greater depths 

 there is small hope of obtaining a supply from that source. Very 

 much the same conditions obtain at Kalgoorlie, and Mr Maitland 

 does not recommend the continuance of any deep borings. There 

 is great demand for water at Cue to work the crushing plants, but 

 the nearest locality from which water can be obtained is Millie 

 .Soak, about ten miles to the north-east. Here is a bed of magnesian 

 limestone, in which there have already been sunk wells that yield a 

 supply of 1000 gallons per diem. The catchment area, however, 

 does not appear to be large, and the quantity of water depends 

 largely upon seasonal rains, so that the bed could not withstand a 

 constant daily drain upon it of a quarter of a million gallons, which 

 is the amount required. From Mr Maitland's refusal to recommend 

 further deep borings we assume that the conditions which govern 

 deep-water-supply in Western Australia are not the same as those 

 that obtain in Sweden, where, as 13aron Nordenskiold has shown, 

 fresh water can always be obtained at a depth of 30-40 metres 

 below sea-level. 



Corn-Midges and their Enemies 



Of high scientific and practical interest is Dr P. Marchal's recent 

 paper, " Les Cecidoinyies des Cereales et leurs Parasites " (Ann. Soc. 

 Ent. France, 1897, pp. 1-105, pis. 1-8). The famous Hessian 

 Ply (Cecidumyia destructor) is naturally treated at greatest length, 

 the three forms of its larva and the formation of the puparium being 

 described and figured with many details. The parasites which are 

 i >f the greatest service in keeping the midges in check, are mostly 

 minute hymenopterous grubs (Chalcids and Proctrotrupids). Among 

 the latter, Trichacis remulus, Walker (parasitic on Cecidomyia 

 Arenac, Marchal) is described in detail. Its first larva is cyclops- 

 like. Three or four of these live on the nervous system of a 

 •cecidomyid larva, and the nerves of the host degenerate with the 



