president's address. 575 



Dividing Range, and also that the volcanic outbursts succeeded 

 the period of heavy sedimentation when the 35,000 feet of Silurian 

 rocks were deposited. 



B. Middle Devonian. — (1) Victoria. After the eruptions 

 ceased subsidence followed to the extent of at least 3000 feet. 

 This must have depressed the greater part of the south-east of 

 Victoria, from Forest Hill to Cape Howe and thence at least as 

 far as Sale, below sea-level. On the sinking sea-floor were laid 

 down, first, coarse angular breccias, rejjresenting perhaps a shore- 

 line, and composed of volcanic material indicating sub-marine or 

 littoral volcanoes, probably the latter, as they are mixed with 

 fragments of slate and sandstone belonging to the older Palaeozoic 

 rocks. Felsite, basalt, red rubbly beds, limestones, and yellow 

 beds representing consolidated felsite mud follow,* the total 

 thickness being from 700 to 1000 feet. Compact limestones, 400 

 to 500 feet, succeed, indicating a cessation of volcanic activity 

 and sugjorestive of clear and warm sea-water free from much 

 sediment. 



The Tabberabbera shales and the Gobannah quartzites were 

 probably formed contemporaneously with the Buchan limestone 

 just described. 



Among the fossils found in the limestones may be mentioned 

 a ganoid placodermatous fish, Asterolejns ornata, Eichwald, var. 

 ausiralis, McCoy. Among the brachiopods, Sjnrifer Icevicostata 

 is specially characteristic. 



Mr. George Sweet of Melbourne has been indefatigable in 

 collecting remains of fossil fish from the Middle Devonian rocks 

 of Victoria, and the publication of Professor McCoy's memoir on 

 them, which has been in preparation now for several years, is 

 being anxiously awaited by Australian geologists. 



(2) In New South Wales Middle Devonian rocks have not yet 

 been recognised, though it is probable that the limestones of 

 Coodra Vale, near Yass, with remains of Coccostean fish, are 

 homotaxial with the Asterolepis limestones of Victoria, 



* Murray, loc. cit. p. 55. 



