180 PROCEEDINGS OF SECTION C. 
justly levelled against the one as the other! Is the Lyelies 
not comparative, and is it not as easy, er as difficult, to 
decide what forms in the Northern Hemisphere show the 
closest affinity with ours, as. it is to decide whether the latter 
are living species or not ? 
‘It is not easy to decide what is the most satisfactory basis 
to adopt for the determination of the age of our Tertiary 
strata, for the faults of what appear to be the only two 
available ones “ must give us pause | 
Tae Fauna or tae OLpest AUSTRALIAN TERTIARY. 
Some of the difficulties may be indicated by a_ hasty 
glance at the fauna, which is extremely rich, but as yet very 
far frora being completely worked out. About fourteen 
years ago Professor Tate summarised his knowledge of the 
constituents of the Older Tertiary Fauna of Australia (Tate, 
88). Under the name “ Older Tertiary’ it may be men- 
tioned that he included those beds which he called Eocene 
and Miocene. Altogether 1519 species of all classes are 
noted, 941 being mollusca. His comparisons are made with 
the Older Tertiary, as he consistently calied it, as a whole, 
and reference may be made to his masterly paper for his 
results, which, it must be remembered, are founded on his 
own knowledge of the fauna in a practically undescribed 
condition. 
At present our so-called “Eocene” has yielded about 
1500 described species, some 600 of them being mollusca, 
and a slightly smaller number being polyzoa. The corals, 
echinoids, aud brachiopods comprise about 52, 35, and 40 
species respectively. So that, to have any weight, com- 
parisons must be very numerous indeed. 
The only two authors who have made any nee number 
cf comparisons of our earliest Tertiary fossils with forms 
occurring elsewhere are M’Coy and Tate, and I think it 19 
probable that in making the comparisens, they did not wish 
to be understood as affirming tha es these were always made 
with forms showing the closest resemblances. Small -refer- 
ence collections, comparacivaly 5 inti libraries, and distance 
from fellow-workers are reasonable SxnOSEs for any imper- 
fections in this respect in work which it 1s far better should 
be done on the spot, and which all agree has been well done 
by these two pioneers in Australian palzontology. 
pra (M’Coy, "74, e¢ seg.) figured and described 53 
species. from the « oldest series and compared 21 mollusca 
with teen cies occurring elsewhere, with the following 
results :— 
