408 ON THE GEOLOGY OP YASS PLAIN'S, (THIRD PAPER.) 



The alternation of gritty and sandy beds with shale and 

 limestone are sufficient evidence of the rising and falling of the 

 land, though the period we are now considering must have been 

 in this part one on the whole, of depression : must have been a 

 general gain of the water upon the land. From the position of 

 the Murrumbidgee beds further westward, this encroachment on 

 the land must have continued long after the period of the Yass 

 Silurian. 



In conclusion I may remark that New South Wales has 

 undoubtedly a Geological history of its o^vn which if we are to 

 learn, it must be from a systematic examination of the rocks in 

 detail by Geological Survey, and not by adopting general 

 conclusions arrived at in other countries, which seem to agree 

 with random observations in this. 



NOTES AND EXHIBITS. 



Mr. Masters gave the following instance of the effect of heat 

 in the development of insects : — He stated that on the L4th of 

 this month, when on a visit to the garden and hothouses of the 

 Hon. James White, at Cranbrook, he had observed a number of 

 SchizorrMna dorsalis flying about, and struck by the appearance 

 of these beetles at a season of the year at least three months 

 earlier than their usual time ; he made inquiries and found that 

 the laiwae had been introduced in the tan used for plunging pots ; 

 the very rapid development of the insects was caused solely by 

 the heat of the beds. The larvte were also found to be very 

 destructive to the plants by passing from the tan to the flowerpots 

 by the hole in the bottom and eating the roots. 



Dr. Cox exhibited fossil teeth of Diprotodon found between 

 Merriwa and Cassilis, at Dunlop's Paddocks, Bow Creek, three 



