OSTRACODS FROM SOME QUEENSLAND TERTIARY BASINS. 
119 
Unfortunately, only a small collection of ostracod-bearing shale 
samples from the Petrie Series has been available for micropalae- 
ontological examination. A few small samples were obtained from 
Houghton’s bore at Lawnton, but most of this material was very much 
crushed and broken up by percussion drilling. Only two samples were 
found on the spoil heap of the old well on portion 190, parish of Warner 
and, although more material was collected from Simpson’s well, E. of 
Bald Hills, it had weathered practically to a soil and almost all the 
ostracods were present only as internal casts. Most of the material so 
far collected has, in fact, come from Brecknell’s bore at Strathpine, 
and this has provided the basis for the micropalaeontological work that 
lias been carried out. Quantitatively, however, the amount of ostracod- 
bearing shale available for study even from this bore was not great and, 
as the material had lain on the surface for several years, it had weathered 
and become still further broken up. 
Although much of the ostracod-bearing shale that has been collected 
is rich in ostracod remains, most of the valves are even more crushed 
and broken than those from The Narrows. An intensive microscopic 
search, however, has revealed a number of identifiable forms which have 
given some indication of the fauna and its affinities. 
In the collection of samples examined, the species present in order 
of abundance are: — Erpetocypris aequalis Chapman, 1935; Cypris 
munduranensis sp. nov. ; Cypridopsis compressa Chapman, 1935 ; 
Ilyodromusf concentricus sp. nov. ; Erpetocypris f subtriangularis, 
sp. nov. 
Discussion. 
Considered as a whole, the known ostracod fauna of this 
series shows a very close affinity with that described above 
from The Narrows Tertiaries. In fact, four of the five species 
identified — namely, Cypris munduranensis, Ilyodromusf concentricus, 
Erpetocypris aequalis , and Erpetocypris f subtriangularis — are found 
in The Narrows Tertiaries. In the presence of the other species, 
Cypridopsis compressa , as well as of Erpetocypris aequalis, how- 
ever, some affinity is shown with the fauna of the Redbank 
Plains Series described by Chapman in 1935. Although Erpetocypris 
aequalis and Cypridopsis compressa are common members of the Petrie 
Series fauna, it must be borne in mind that most simple, smooth-shelled 
Cyprids are long-ranged, so that the occurrence of these species needs 
not necessarily suggest approximately equivalent ages for the two series. 
In fact, the presence of these two ostracods in all the Petrie Series 
ostracod-bearing shale at present available suggests that they are 
moderately long-ranged forms. Accordingly, in evaluating the Petrie 
Series ostracods as a criterion of age, it is necessary to consider all 
members of the fauna. When this is done, there is definitely a much 
closer relationship between the Petrie Series and The Narrows ostracod 
faunas than between the former and that of the Redbank Plains Series. 
From this similarity in their ostracod faunas, and the fact that two 
of the species common to them are moderately short-ranged forms, it 
seems that the Petrie Series is equivalent in age to The Narrows 
Tertiaries. Since a probable Miocene age has already been suggested for 
The Narrows Tertiaries from a study of its ostracod fauna (see above), 
a probable Miocene age, then, can also be postulated for the Petrie Series. 
T 
