62 Proceedings of the Royal Society of Victoria. 



The species of six molluscs in the above list is doubtful, 

 owing to the badly preserved state of the specimens, and 

 the remarks which follow refer only to the remaining 110 

 species. The number of new species gathered by us was 24-, 

 which with 8 others previously discovered by Mr. Gregson, 

 makes a total of 82 new species from these beds. Of the 

 110 species, 91 are extinct, and 19 are still living. In 

 estimating the age of the deposit by the percentage system 

 of Lyell, it is, of course, allowable to reckon only the 

 Mollusca proper, and therefore, the 8 species at the bottom of 

 the list will be neglected. We thus have 86 extinct, and 16 

 living species of Mollusca available for calculation. The 

 following is a summary of their distribution in time : — 



Extinct Species— 



Ranging from Eocene to Pliocene . . . . 3 sjoecies 



,, Eocene to Miocene .. .. 12 ,, 



,, Miocene to Pliocene .. .. 2 ,, 



Recorded from Eocene strata only .. . . 4 ,, 



,, Miocene „ . . , . 33 ,, 



Restricted to Jemmy's Point beds . . . . 32 ,, 



Living Species — 



Ranging from Eocene to present time .. .. 3 ,, 



,, Miocene ,, . . . . 8 ,, 



Restricted (as fossils) to Jemmy's Point beds . . 5 „ 



Total . . 102 



The terms Eocene, Miocene, and Pliocene, are used merely 

 to indicate the relative ages of our various tertiary deposits, 

 as shown by the percentage of recent shells contained in 

 them, and not to imply synchronism with strata so narhed 

 in Europe. The percentage system of determining the 

 horizon of a bed is, of course, as applicable to the Austialian 

 tertiaries as to those in other parts of the world. The 

 Molluscan faunas of Schnapper Point, Jan Juc, Muddy 

 Creek, and the Murray cliffs, are as rich as those from the 

 Paris and Vienna basins, and will afford to the patient 

 collector ample materials for their subdivision into well 

 defined groups. The argument for the j^ercentage method 

 of classifying tertiary strata is very clearly stated by 

 Professor Hutton in an article upon the Wanganui System 

 of New Zealand, from which I quote the following 

 remarks : — 



" The value of taking the recent species of Mollusca in a 

 tertiary rock, as a test of its relative age, has sometimes 



