f)32 GEOGRAPHICAL DISTRIBUTION OF AUSTRALIAN BATRACHIA, 



and all that that implies. In other words a number of hardy 

 species seem alike able to flourish under such diverse conditions 

 of life as prevail in the subtropical Northern River Districts, and 

 in the dry country of the western plains. Others seem unable 

 to maintain themselves away from the favourable conditions 

 which attain a maximum in the coastal district and on the 

 eastern side of the Tableland ; while others again seem only 

 perfectly at home in a region where the cycle of events may be 

 summed up as devastating floods, disastrous droughts, and inter- 

 vening good seasons, in varying intensity. 



In an interesting paper entitled " Notes upon the History of 

 Floods in the Kiver Darling" (Journ. and Proc. Roy. Soc. of 

 N. S. Wales, 1886, xx. p. 155), Mr. H. C. Russell, B.A., F.R.S., 

 has brought together the records from all available sources, a 

 perusal of which indicates in a very suggestive manner the 

 extremes to which animal life in the interior is exposed. When 

 in a severe drought, as reported by Mr. Russell's correspondents, 

 the country becomes a desert, the swamps, lagoons, and the tribu- 

 taries of the Darling are dry, and the river itself is reduced to the 

 condition of a chain of waterholes sometimes miles apart and in 

 places salt, it would appear as if at any distance back from what 

 is left of the river frogs must over a considerable area run great 

 risk of absolute extermination unless their sestivating capabilities 

 have become correspondingly developed. The survivors get their 

 opportunity again with a big flood, which may inundate the back 

 country to a distance of twenty, forty, or even seventy miles, 

 once more filling the swamps and lagoons. A succession of good 

 seasons encourages a flux of animal life for a time, with the 

 inevitable ebb when a drought gives the check, the cycle, as Mr. 

 Russell thinks, occupying a perioil of about nineteen years. 



Several of the characteristic species of the Plains are not yet 

 recorded from the southern colonies, and in N. S. Wales they 

 have not all migrated from the coast. If not developed in the 

 subregion there must have been migration at some time from the 

 north. But this and other cognate questions cannot be satisfac- 

 factorily considered until more is known of the fauna of Queens- 



