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zoic forms rather than to any other. But our Australian corals are a 

 group in themselves, with really no very strong affinities with any 

 hitherto described. None of those have pali ; some have an epitheca, 

 and others are destitute of it, but the fossils amongst our Australian 

 group which have any of tbese features are sure to differ in every other 

 respect in a remarkable degree from them. It is, as I have already re- 

 marked, this natural extension that we might expect to which our 

 systems of classification will have to submit, as our knowledge of the 

 variation of the plan of nature becomes wider. It is on this account that 

 we cannot form any conclusions, or at least any safe conclusions, as to the 

 age of our beds from paleontological considerations alone. The resem- 

 blances to the fossils of tertiary ages in the northern hemisphere are few 

 and of a trifling kind, while the differences are very numerous and wide. 

 We are baffled by the difficulty of comparing things which have little or 

 nothing in common. But while this is true, we may institute comparisons 

 upon paleontological grounds alone between our various Australian deposits. 

 Thus, this group of Trochosmiliacece shows us that the Aldinga formation 

 has fossils which intimately connect it with the Australian group of ter- 

 tiary rocks. No species can be identified with those already described, 

 though one, Conosmilia contorta, may be only a variety. Cyathosmilia is a 

 kindred genus with pali. Bistylia is a little more divergent, for it has 

 distinct costa like Parasmilia, but with a bistyliform columella. 



Plesiastrcea is entirely a recent form, and we may say Australian as 

 well, for the species described which are not Australian are either from 

 the Pacific or Indian ocean. There is one fossil species known in the 

 Belgian miocene. The fossil species here described is very close to our 

 living form, now common on the same parts of the coast. 



Though no existing species has been yet found, and though the 

 genera even are, as far as we know, for the most part extinct, yet I 

 think we are justified in calling the coral fauna an Australian Tertiary 

 one — the forms of life approximate to a Mesozoic character, in my 

 opinion, though I form it upon slight grounds, and I should say that we 

 have one of our oldest tertiary fauna represented. The corals are par- 

 tially such as would grow in a deep sea at the present time, but Cladocora 

 Plesiastrcea are" merely litoral species, and probably also Amphihelia. 

 There are no reef-building forms amongst them, for though the three 

 last named are branched corals, yet they never grow to any size beyond 

 insignificant tufts. They do not evidence a climate different from the 

 present climate of South Australia, that is if the animals were subject 



