142 Chapman, The Palcvozoic Flora. [vo["^xxxiv 



From the associated Archccocyathiiuc iii the limestone", this 

 algoid species belongs to the Lower Cambrian, and, in fact, is 

 closely related to another of the same genus found in the Lower 

 Cambrian of Siberia by Van Toll. 



In Ordoviciax times the Australian coast-line covering parts 

 of South Australia, Victoria, and New South Wales, as well as 

 Tasmania, was fringed with extensive black mud-flats and 

 shallow seas, in which flourished abundant growths of the 

 plant-like animals called Graptolites. Remains of undoubted 

 plants, however, seem to be unknown in these beds, the Grapto- 

 lites either superseding the plants in this area or else surviving 

 the ordeal of fossilization by their more durable chitinous 

 peridermic covering. Tliat sulphur bacteria must have been 

 present in these dark shales is fairly evident from a study of 

 the conditions prevailing at the present time in an area like 

 the Black Sea,* and, in fact, whilst examining some verv thin 

 slices of Victorian Ordovician slate under a high power, I was 

 struck by the appearance of some minute objects having a 

 resemblance to certain fossil bacilli found in a coprolite of 

 Permian age by Renault and Bertrand.f These bodies are 

 long, sausage-shaped, slightly curved in some cases, and measure 

 I m. in diameter. As in modern land-locked areas, there also 

 probably existed a plankton consisting of lower animal organ- 

 isms and diatoms. 



Passing upwards to Siluri.w times, large tracts of the 

 Australian continent were covered with shallow to moderately- 

 deep seas, especially in southern and central \'ictoria, in 

 southern and central New South Wales, in Queensland, and the 

 Northern Territory. The oldest Silurian is that of the Mel- 

 bournian division, equivalent to the Llandovery or Valentian 

 of Europe, and probal)ly almost confmed to the Melbourne 

 bed-rock and the sandstone of Heathcote, although some 

 locally-developed beds in New South Wales may turn out to 

 be of similar age. In these shallow seas were deposited sand- 

 stone with false bedding, and pyritous and limonitic nuulstones. 

 Later on, in Yeringian times, the equivalent of the Wenlockian, 

 deeper water conditions seemed to have predominated, as 

 seen in the coral hmestone of Lilydale and Waratah Bay, Loyola, 

 and Toongalibie, in Victoria, and of the Federal Territory in 

 New South Wales. The shallow water and marine deposits of 

 both Alelbournian and Yeringian stages contain numerous 

 fucoids referred tf) the genus Bythotrephis. Tiiere is some 



* See Schuchert, " I'roc. Amer. Phil. Soc," vol. liv., 1915, p. 259 ; also, 

 Andrussow, " La Mcr. Noire," Guides des Excursions, Vile., Cong, Geo). 

 Internal. .St. Petersbourg, 1897, Art., x.xix. 



t " Compt. Rend.," vol. cxix., 1894, p. 377; also, Seward, "Fossil Plants," 

 vol. i., 1898, p. 13s, fig. 2?>b. 



