^l^.l['] Chapman, Geological History Australian Plants. 131 



notably in East Gippsland, has been preserved in the form 

 of sihcified tree-trunks. These occur in a more or less water- 

 worn condition, mingled with the gravels of the Bairnsdale to 

 Orbost area. Two of these ancient forms of trees have been 

 identified by the writer * as Eucalyptus cf. melliodora, Cunning- 

 ham (Yellow Box), from Bruthen, and E. aff. piperita, Smith 

 (Peppermint Gum), from Mallacoota Inlet. Their microscopic 

 structure is wonderfully preserved, although occasionally 

 broken down by chalcedonic crystallization, probably where 

 the tissue was already partially decayed when petrifaction 

 took place. 



Newer Volcanic Tuffs with Leaves and Fruits. — At Warrnam- 

 bool volcanic tuff occurs, containing impressions of Eucalyptus 

 leaves. There is a fine block of this exhibited in the galleries 

 of the National Museum. In the scoria ceous tuff of Mount 

 Gambler, South Austraha, some exceptionally well preserved 

 fern-fronds of Pteridium aquilinmn (Bracken) and leaves of 

 Banksia marginata (Silver Banksia) were found, the occurrence 

 of P. aquilinum in these prehistoric beds proving its claim as 

 an indigenous and not an imported plant. An indul^itable 

 impression of the end of a Casuarina cone (near ('. stricta) in 

 lava from Yandoit Hill has recently been described in the 

 pages of this journal. f This is another remarkable instance 

 showing how slowly the heat from the lava escapes when in 

 contact with hgneous material like plant-stems and woody 

 fruits. 



Diatomaceous Deposits of Pleistocene Age. — These occur, as 

 a rule, filling up depressions in the basalt flows of late Tertiary 

 age, or else interbedded between intermittent flows ; in other 

 cases they are found, generally in an impure state, in back- 

 waters of creeks covered by river silt. The best-known locali- 

 ties are, in Victoria, at Talbot, Craigieburn, Sebastopol, Port- 

 land, Lancefield, and South Yarra ; in New South Wales, at 

 Cooma, Barraba, and the Richmond River ; in Queensland, at 

 Pine Creek. The genera, except in the case of South Yarra, 

 are of the well-known fresh-water types, Mclosira, Navicula, 

 Cymhella, Synedra, Tabellaria, Stauroneis, and Gomphoncma 

 being best represented, and there are usually present spicules 

 of the fresh-water sponge, Spongilla. The localitiis have 

 been excellently summarized for Victoria by Mr. D. J. 

 Mahony.J 



Till! writer has lately found the remains of a fresh-water 

 alga, apparently referable to Cladophora, in the Richmond 

 River deposit, and Von Mueller has already described seeds, 



* Id., ibid., vol. xx.xi., part i, IQ18, pp. 172-175. 

 t Vict. Naturnlisl. vol. xxxi., iQi-t, ]). 89. 

 I Bull. Geol. Surv. Vict., No. 2(>, lyu. 



