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bluish limestone, several hundred feet in thickness. On the 

 Sellick's Hill road these beds are largely covered with travertine, 

 but are exposed in a small quarry close to the road, where the 

 stone has been worked for lime-burning. Better sections of these 

 beds can be seen in the creeks which traverse the outcrops 

 further to the north-east. They are not conspicuously fossiliferous, 

 and the stone is very compact, but in an hour's careful search in 

 the Sellick's Hill quarry three small mollusca and a few Archao- 

 cyathina were obtained. 



The upper fossiliferous horizon is a remarkable coralline bed, 

 100 feet in thickness. The calices of the anomalous Archceocya- 

 thince are crowded together in a manner that must have formed 

 a true coralline reef in the Cambrian seas. The solidity and 

 refractoriness of the matrix rendered it quite impossible to 

 extract these corals from their bed, and the only method in which 

 they can be successfully studied is by polishing and sectioning 

 the rock in which they are entombed. Such a method of in- 

 vestigation is a work of time, and consequently the palaeontological 

 results await future elucidation. 



The vertical range of the fossiliferous section in the beds 

 marked " e " to " g " in the accompanying table is estimated at 

 800 feet. 



This discovery of Lower Cambrian fossils in the Sellick's Hill 

 Ranges gives a fresh interest to a reputed discovery of fossils in 

 this neighbourhood mentioned by Tenison- Woods in his 

 " Geological Observations in South Australia," p. 20, where, 

 speaking of the Mount Lofty Ranges, he says : — " No fossils 

 have been found except at one portion of the range, about thirty 

 miles south of Adelaide. I was informed that the fossil was a 

 Pentamerus oblongus. This would be characteristic of the lowest 

 division of the Upper Silurian rocks. The person who found it 

 is since deceased, so that the observation cannot be traced further 

 or verified, unless new discoveries are made. With this excep- 

 tion ; if, indeed, it can be considered such, nothing is known of 

 the age of the rocks on this range." 



The locality indicated for this fossil by Tenison- Woods, 

 although indefinite, is sufficiently precise to make it highly pro- 

 bable that it was obtained from some part of the Cambrian out- 

 crop in the Sellick's Hill Range. The species mentioned is 

 correctly referred to the Upper Silurian, a formation considerably 

 higher in the geological scale than the one we are now dealing 

 with. To explain the discrepancy, we must infer one of two 

 things — either that fossiliferous beds higher in the geological 

 series than the Lower Cambrian occur in the ranges, or otherwise 

 the shell was wrongly determined. The latter is most likely to 

 be the case. We have no information on whose judgment the 



