142 HORN F.XPRDITION — SUMMAHY. 



Pl.iiiarians ni- Poripatiis or cvon the wido-sprrad larnl Aiiijiliipocl to exist in sueli a 

 lenioii. 



Next lie liecoines wearied with the unsuccessful search after insects on flower- 

 ini,' shrulis, though such as Cassias and Rreninphilas are ahiinilant and attractive 

 enout;ii, and day aftei- day he linds the same forms of life. Every water-hole, every 

 loamy plain or sandliill yields a wearying;', monotonous and small series of anim;ils 

 until he l)egins to realise that the fauna is characterized hy the entire ahsence of 

 the rich sei'ies of species of tlu^ coastal districts and the presence of a relatively few 

 dominant species which are evidently capahle of adaptin;^' themselves to conditions 

 of the most unfavoural)l(^ description for animal life. 



Tn the wet season the fauna changes as if hy magic, insects formerl}' uns(>en 

 come about in swarms, fresh water Crustacea crowd the clay-pans and water-holes, 

 caterpillars in tliousands creep aliout, the majority of them simply falling a ]>rey 

 to the lizai-ds, frogs and birds which increases with like I'apidity. At the same 

 time though animal life is now abundant it is composed of relatively few species, 

 each existing in eirormous numbers. Prol)ably towards the close of the fav(juralil(> 

 season a horde of migratory rats will pass like a wave across the country, disap- 

 peaiing into tlie dc|)lhs <tf the desert, wheic they perish. For a time the small 

 marsupials will be more or less abundant, but soon they also will disappear to 

 fcstivate during the dry season or only to come out from their hiding places during 

 the cool of the night — the majority of them probably perishing bef<ire they reach 

 maturity. 



Rapidly the country assumes its dry state, and the only animals left are the 

 hardier forms which can withstand the heat and dryness, and the few inhabitants 

 of the deeper and scattered water-holes. 



If the drought lie abnormally prolonged then even the hardiest animals will 

 sufTer, and the fauna will be so reduced that it uiay take some time before 

 increased fertility on the part of the survivors and the influx of immigrants from 

 the broad belt of land enclosing the central region will make good the deficiency. 



Probably, what is certainly ti'ue of the plants, holds good in the case of 

 animals, and that is that the struggle for existence is not of such a complicated 

 nature as in many other parts. After the rain falls, a caterpillar or insect or fi-og 

 for example has no lack of food — there is plenty for all — though of course they are 

 each liable to fall a prey to biids oi' reptiles or m.ammals. There does not seem 

 indeed to be any attempt made except perhaps on a most limited scale, at anything 

 like piotecti\'e colouration. (-irasshopj)ei'S and insects crawl about in thousands 



