720 THE DRAGONFLIES OF SOUTH-WESTERN AUSTRALIA, 



begin to dry up rapidly. In less favoured localities the river- 

 beds become quite dry in the summer, with possibly a pool of 

 water here and there; and even in the best localities I found very 

 few of the creeks actually running, 



A glance at the map (Plate xxxiv.) shews that a fair number 

 of rivers drain the South- Western District. Taking them in 

 order from north to south, we have the Swan, Serpentine, Murray, 

 Collie, Preston, Margaret, Blackwood, Warren, and Frankland. 

 These may all be classed as mountain streams; for they all drain 

 the plateau of the Darling Ranges, which extends from north to 

 south at a distance of twenty to forty miles from the coast, except 

 at Cape Naturaliste, where a spur runs out right to the Cape 

 itself. The sources of the longer rivers would therefore be at 

 elevations of from twelve to fifteen hundred feet, and in the 

 winter they bring down a big volume of flood-water. However, 

 the river channels are narrow and deep, and tlie only stream 

 that has any pretensions to being a really fine river is the 

 Blackwood. At Bridgetown, a hundred miles from its mouth, it 

 carries all through the year a large volume of water and is in 

 many places over one hundred yards wide. 



Besides these running mountain-streams, all of which carry 

 nearly the same Odonate fauna, we have the coastal lagoons, 

 some of which are fresh, like Mungar's Lake, near Perth. These 

 carry a somewhat different Odonate fauna. A third class, the 

 marshes and swamps, usually very rich in Odonata, is practically 

 absent, except in the Warren River district and around Lake 

 Muir, where there are some fine tracts of swampy country. 

 These are very inaccessible, but I was able to work the fringe of 

 them at Wilgarrup, where there is a small brook running through 

 some splendid marshy tracts. This is one of the best collecting 

 places I found in Western Australia. 



Taking as my base the South-Western railway line (that is the 

 line from Perth to Busselton and Bridgetown, running almost 

 due south) I was able to work from Perth down to Cape Leeuwin, 

 and inland to Bridgetown and beyond, w^ith care arid thorough- 

 ness. I was unable to get farther eastward to Albany, but tlie 



