BY PROFESSOR STEPHENS, M.A., F.G.S. 935 



This at least we may now assert of the Hawkesbury formation, 

 that if it had, as Mr, Wilkinson's observations render 

 probable, a glacial period, it had also one or several eras of 

 genial warmth and moisture. The Planorbis to which reference 

 has been already made, the Unioniclaa which have been discovered 

 in the Wianarnatta rocks, the highly carbonaceous and even 

 bituminous character of much of the Parramatta and Kenny 

 Hill Shales, and still more emphatically the extraordinary plant 

 from the Parramatta River, described by Baron von Muller as 

 Ottelia praterita, (Jour. Roy. Soc. N.S.W., 1879, p. 95), and a 

 large fruit recently obtained by Mr. Wilkinson, demonstrate this. 

 Now here is another singular correspondence between our Hawkes- 

 bury s and the Trias of Europe. 



Both in the preceding (or Permian period) to which our New- 

 castle coal is reasonably referred, and in the Triassic we find, all 

 over the world, evidences of ice. And at the same time we find in 

 the organic remains abundant evidence of heat. It can hardly be 

 doubted by any unprejudiced person that both these periods, 

 whose records testify to enormous and now-a-days unparalleled 

 changes in all plant and animal life, were also times of enormous 

 and perhaps unparalleled change of climate, during which northern 

 forms were driven to the south, with vast loss not only of indivi- 

 duals, but of species, to be driven back again in the course of 

 another ten thousand years or so, losing on their road the greater 

 portion of their whole army. This is the true solution of the 

 strange break between the Palaeozoic and Mesozoic time, and is 

 strongly corroborated by the fossil now before us; while Dr. J. 

 Croll has demonstrated the fact on different grounds. 



When this family lived and flourished somewhere north of the 

 equator, with Hyperodapedon, Ceratodus, and other contemporaries, 

 cold and inclement seasons began to increase their severity ; and 

 as the Labyrinthodont clan were entirely carnivorous, they had to 

 travel south after their food, since it also had its own power of 

 locomotion. And so — after thousands of years — they found them- 

 selves in South Africa, South America, India, and Australia ; and 



