RELATIONSHIP OP AUSTRALIAN TERRESTRIAL FORMATIONS. 307 



associates differing widely in cliaracter from those met with in tlie 

 last station reached by them, in their long process of migration. 

 For my own part, I do not see what other explanation can be 

 given which would satisfactorily account for the gaps, inversions, 

 and lack of biological progression in any one regional centre, 

 wlien viewed in relation to the order and grouping of organism in 

 far distant regions. 



The acceptance of separate centres of specific origin from one 

 independent pair in conjunction with time consumed in migra- 

 tion, does of necessity involve such inharmonious relationships, 

 when the view is restricted to any one spot on the earth's 

 surface ; but it is perfectly compatable with orderly relative 

 biological progression when concerned in relation to all centres, 

 of the globe. 



Let it be firmly borne in mind that the principles contained in 

 these reflections are neither new nor fanciful. They flow natur- 

 ally and consistently from conceptions regarding the doctrine of 

 single specific centres, firmly held and advocated by Sir Henry De 

 la Beche nearly fifty years ago. Edward Forbes, according to 

 Huxley, firmly held to this view, for he was in the habit of 

 asserting that the similarity of the organic contents of distant 

 formations was prinid facia evidence, not of their similarity, but 

 of their difference of age, and Huxley himself, whose name is 

 always associated with Darwin, has long devoted his clear reasoning 

 mind to establish the same ideas. Similarly, the writings of Sir 

 Koderick Murchison, Jukes, Blandford, Ettingshausen, Starkey 

 Gardner, Feistmantel, Daintree, Prof. Hutton, Prof. Judd, and 

 many others could furnish strong support in favour of the concep- 

 tions now brought specially under the consideration of this 

 Association for the purpose of evoking discussion. 



In making use of the phrases "stages of biological progression," 

 and " stages of stratigraphic succession," there is also much 

 danger. 



We can conceive of the development of the lower to the higher 

 formsof life occ urring in a broad harmonius order as under : — 



1. 2. 3. 4 



Plants — Thallogens. Ferns, Mosses, Cycads, Angiosperms. 

 and Lycopods. and Conifers. 

 Invertebrates. Vertebrates. 



Animals — Protozoa; Molluscs, etc. Gill-breathers; Lung-breathers. 

 Whatever gaps are found in the simple series, it is conceivable 

 that the order might be found without inversion in all regions, 

 and so far it is possible for stages of stratigraphic succession 

 being recognised, which would in any country, broadly correspond 

 with such stages of biological progression. But if the correspond- 

 ence between orderly biological progression, and orderly strate- 

 graphic succession, is expected to coincide in regions far apart, 

 beyond these general lines I am convinced the results would be 



