58 Proceedings of the Royal Society of Victoria. 



theatre surrounding an extensive flat, through which the stream 

 pursues a very tortuous course. Close at hand is the basalt 

 capped hill called Dog Island, while in the distance the narrow 

 gorge of the Dog Rocks bounds the view. The name Dog 

 Island, commonly applied to the hill just mentioned, is quite 

 inappropriate, as it is not really an island at all, the river 

 flowing on its west and south sides only ; on the north and east, 

 the land, though slightly depressed, is still much above the river, 

 which, we are assured, never inundates it, even in the highest 

 floods. 



Further remarks to be made upon the rocks of Dog Island are 

 postponed till the principal eocene sections in the vicinity have 

 been described. 



At the Amphitheatre or Bull Island section (No. X.), the 

 strata exposed on the bank are ; — 



Ironstone drift ... ... ... 40 feet 



Limestone, masked by reddish clay ... 50 ,, 



Banded limestone, with eocene fossils ... 40 ,, 



Marls, yielding an abundance of fossils, 



. . 90 



with blocks of hard limestone " 



River alluvium ... ... ... 20 ,. 



Total height of bank ... 240 feet 



In the marls are disseminated small quartz pebbles, while 

 fragments of ironstone, no doubt derived from above, occur on 

 their surface. 



The water level at the foot of the bank is 80 feet above our 

 datum line, and the upper bands of limestone here thus reach a 

 greater elevation than similar I'ocks at the top of the eocene in 

 the Shelford Bridge and Red Blufi" sections. So also the gastro- 

 pod bed at the base of the Red Bluff is lower than the marls of 

 Bull Island; It is probable that these marls do not extend far 

 below the surface, as silurian rocks crop out in the river bed a 

 few chains to the north. 



Nearly all the fossils quoted in our list were obtained from the 

 amphitheatre and Red Bluff sections, which may be taken as 

 respectively typical of the deposits to the north and south of 

 Shelford. It is apparent that, though largely similar in both, 



