178 Proceedings of the Royal Society of Victoria. 



That the above list of fossils is a short one, as compared with 

 those usually supplied for the tertiary deposits of the province 

 must be attributed to the difficult nature of the material in 

 which they are embedded rather than to the scarcity of the 

 forms present. Many of these, from their small size, or indefi- 

 niteness of the preserved outlines are quite unrecognisable, while 

 for others models have to be prepared. Even with the aid of 

 these, the species, and occasionally the genus also, may still 

 remain doubtful, especially in the case of bivalves, where the 

 hinge characters can rarely be made out. 



In discussing the horizon of the strata we propose to take 

 account only of those fossils the distribution of which is definitely 

 given in the table. Eighteen species are thus available, of which 

 eight are confined to the miocene division of the tertiaries at 

 Muddy Creek, Jemmy's Point, Aldinga Bay, or the Murray 

 River ; while many of the remainder though present also in the 

 eocene, are in reality specially characteristic of the miocene. 

 With only eighteen species as a basis for calculation, the 

 percentage of living forms represented would of course be an 

 unreliable test of geological age. As a fact, no undoubted 

 recent species appears in the list, though it may be mentioned, 

 that one of them, viz., Nucula tenisoni, formerly known as 

 N. tumida, T. Woods, is regarded by Mr. Pritchard as both 

 recent and fossil.* Under these circumstances reliance is placed 

 upon the correlation of the fauna with that in other deposits, 

 which, if correctly given in the above columns, indicates a 

 miocene horizon for the Shelford Conglomerate. On strati- 

 graphical as well as on palseontological grounds, the deposit 

 must be separated from the neighbourhing eocene, while to be 

 even late pliocene, it should show a large proportion of recent 

 shells. Its relation to the accompanying igneous rock has next 

 to be considered, and with reference to this our hesitation in at 

 once classing the strata as miocene, when first met with, was 

 chiefly due, since previous conclusions concerning the age of the 

 basalt are thereby called in question. 



The position of the outcrop, as well as our theory of the 

 sequence of the rocks is illustrated in the appended sketch, 



* Roy. Soc. Vic, vol. viii., p. 128. 



