141 
If we now examine the Eocene strata of Aldinga (and 
Adelaide) in the St. Vincent Gulf area of South Australia we 
observe, as shewn in the Table of Fossils published herewith, 
that amongst many of the old familiar Muddy Creek forms, a 
large number of new ones make their appearance—to such an 
extent, indeed, is this the case that the two faunas are really in 
marked contrast. Compared with the wide. spread fauna of 
the Muddy Creek Eocene, that of Aldinga, as a whole, is much 
more restricted geographically, as, except at Cape Otway, few of 
its characteristic fossils are present in other deposits. From this 
fact alone it might perhaps be inferred that the Aldingian is the 
older of the two contrasted faunas, remnants of it only having 
survived toa later period. The recent discoveries made by Mr. 
Edwd. Clark, B.Sc., in the Ninety-Mile Desert of South Australia, 
already alluded to, and which are published in the present issue 
of the Society’s Transactions tend to confirm this view. Having 
been allowed by the courtesy of the author to peruse the manu- 
script of his article we have little doubt concerning the correct- 
ness of his conclusions, viz., that in all probability the inferior 
beds of Aldinga (and Adelaide) underlie the Mount Gambier and 
Murray River limestones, and consequently therefore the deposits 
we have correlated with them at Muddy Creek. 
Amongst the various Eocene beds hitherto examined those at 
Muddy Creek and Aldinga exhibit the greatest diversity in their 
faunas, as, though they contain many species in common the 
restricted ones are specially numerous. Both have been well ex- 
amined and may be regarded as typical representatives of the 
older and younger faunas respectively, with which, therefore, 
other Eocene sections can be well compared. With the notable 
exception of Cape Otway, the Muddy Creek type of fauna is con- 
spicuous in most of the Victorian Eocene sections, that of 
Aldinga being feebly represented. The same remark applies to 
the Murray beds in South Australia, and also to those at Table 
Cape in Tasmania. In the case of some of the best known sec- 
tions, the relative representation of the Aldingian fauna can be 
approximately estimated, and it is curious to note that the per- 
centage of characteristic Aldinga shells present in them seems to 
decline from Cape Otway to Table Cape, Spring Creek, and 
Geelong, and thence westward to Birregurra, Camperdown, and 
Gellibrand R., along a former strait or channel, which, as will be 
shown later on, existed in the old Eocene sea. 
Our estimate is arrived at by taking account of those Aldingian 
shells which have not so far been recorded from Muddy Creek, 
though they are represented in one or other of the intermediate 
outcrops. Only well authenticated species can be quoted, which, 
according to our records, number 46. The distribution of these 
is shown in the following table :— 
