Benson.—-Palaeozoic and Mesozoic Seas in Australasia. 23 
The extensive fauna of the Silurian rocks of Victoria has been studied in 
detail by Chapman (1908, 1913, 1916). The Lower Silurian (Melbournian) beds 
occur in the centre of Victoria, running northwards from Melbourne. They 
consist of mudstones and sandstones exhibiting a mixed Wenlock and Llan- 
dovery fauna.. Some 135 species have been recorded. The archaic trilobite 
Ampyz, and an Шаепиѕ allied to an Upper Ordovician form, are associated 
with Monograptus priodon, Botrycrinus, Palaeaster, Palaeechinus, Camaro- 
toechia, Lingula, Nucleospira, обесена. pe many molluscs. The Upper 
Silurian (Yeringian) beds ather more to the east than the former, 
extending into Gippsland. The comprise Sinton, mudstones, and lime- 
stones, from which 200 species of fossils have been obtained with the facies of 
4_ SILURIAN 
UT i PERIOD 
Е] Land Area 
(RS) Upper Silurian Sea 
Lower Silurian Sea 
[3] Exposures cf marine sediments 
————— 
the Wenlock limestone and Ludlow shales. Monograptus riccartonensis and 
M. convolutus, Favosites, Heliolites, Clathrodictyon, Actinostroma, Atrypa, 
Chonetes, Orthis, Pentamerus, Platystrophia, сс оеро, numerous mol- 
luses, Bronteus, Cheirurus, Encrimurus, Phaco s, and many ostracods 
occur in this rich fauna.* In the west of Gippsland there are shales 
containing Panenka, Styolia, Tentaculites, and Kionoceras in a small fauna 
of eighteen species which may represent a still higher horizon in the 
Silurian series; but Whitelaw (1916) has shown that these are overlain woy 
Mein of. coriis в ichelinia and Phillipsi aed, W re more abundant in 
the i the Siluri n rocks of the Northern Hemisphere, 
of Plewrodictyum, which is there confined to the Devonian his constrains us 
nstrains | 
that certain forms of life appeared among the Gothlandian and Wenlock 
facies earlier in the Southern than in the Northern Hemisphere, and migrated thence | 
during the transition period between Silurian and Devonian e epochs ^ ке 1920), 
