536 NOTES ON AUSTRALIAN EARTHWORMS, 



may be that the volcanic outbursts at all three spots were contem- 

 poraneous, and that subsequently all three localities were stocked 

 under similar circumstances, and from the same source, and were 

 afterwards isolated by denudation, so that the worms having lived 

 under very similar conditions may not be very different. (1) 



I do not know for certain whether the rich soil of the Burrawang 

 district forms a completely isolated tract, though on the map this 

 appears to be the case, or whether it does not merge into that of 

 Illawarra, and this again into some other ; (2) but that of Mount 

 Wilson certainly does. As the worms I have described seem more 

 or less restricted to these fertile spots, which must have been 

 stocked in the first instance from the then surrounding areas> 

 possibly the existing worms are simply the well-grown and robust 

 descendants of ancestors which long enjoyed a generous diet, 

 and the surviving remnants of a once more widely spread worm- 

 population whose limits have since been narrowed by the work of 

 denudation, as much of the superficial area of the Blue Mountains, 

 except perhaps in some of the gullies, is probably destitute of earth- 

 worms at the present time. 



(1) Similar remarks are applicable to Mt. King George- Speaking of 

 this neighbourhood Strzelecki says : — "Between these ranges lie yawning 

 chasms, deep winding gorges, and ff rightful precipices. Narrow, gloomy, 

 and profound, these stupendous rents in the bosom of the earth are 

 inclosed between gigantic walls of a sandstone rock, sometimes receding 

 from, sometimes frightfully overhanging the dark bed of the ravine, and its 

 black silent eddies, or its foaming torrents of water. Everywhere the 

 descent into the deep recess is full of danger, and the issue almost 

 impracticable. The writer of these pages, engulphed in the course of his 

 researches, in the endless labyrinth of almost subterranean gullies of Mt. 

 Hay and the River Grose, was not able to extricate himself and his men 

 until after days of incessant fatigue, danger, and starvation. " (Phys. Desc. 

 of N.S.W. and Van Diemen's Land, p. 57.) 



(2) On the Geological Sketch Map accompanying Mr. Wilkinson's "Notes 

 on the Geology of N.S.W.," no large extent of volcanic rocks is shewn in 

 this neighbourhood, but several pei'/ectly isolated patches are marked as 

 lying between the Railway and the coast. These, however, as regards 

 their extent and limits, are probably only represented diagrammatically, 

 the map being on too small a scale to allow of its being otherwise. I cannot 

 identify any connection between Burrawang and either of the patches 

 figured. 



