112 PROCEEDINGS OF THE ROYAL SOCIETY OF QUEENSLAND. 
The Narrows. The samples examined were submitted by the Queensland 
Geological Survey, and were those selected from the regions where 
ostracods showed in quantity in the cores from Bores Nos. 1, 3, 4, 5, 6, 
12, 13, and 14. 
The Tertiaries of The Narrows, centred 15 to 20 miles N. of 
Gladstone, occupy a narrow belt of country on both sides of the strait 
that separates Curtis Island from the mainland. The area on the 
mainland lies largely within the parish of Targinie, but extends to the 
S. just into the parish of Calliope, and to the N.W. into the parish of 
Bundle, while the part of the basin on Curtis Island lies within the 
parishes of Curtis and Monte Christo. All the above parishes are in the 
county of Deas Thompson, except that of Calliope, which is in the 
county of Clinton. Topographically the country is lowland, the surface 
in most parts being not more than 50 feet above sea level. 
Associated with the ostracods in these Tertiary shales, many of which 
are oil shales, gastropods belonging to the freshwater Planorbis 
group and fragmentary fish remains have been found. The association- 
of fossil fish with ostracods in the same strata is not unnatural, however, 
for recent zoological study has shown that they are an important source 
of food for fish today. Coprolites, which may have come from such 
freshwater reptiles as crocodiles or chelonians, also have been found in 
the bore-cores. 
Although the ostracods are very abundant in many of the samples 
they have generally been found to be crushed and broken. Some well- 
preserved individuals, nevertheless, have been found, but these are 
relatively uncommon, and usually occur in the better quality oil shales. 
With reference to habitat, in seems that, in most cases, The Narrows 
fossil ostracods could have no other origin than burial in situ. It has 
been observed, also, that while they are generally more abundant in the 
oil shales, they are quite common in some of the non-bituminous shales 
in the bore-cores. They are, however, rare and completely absent from 
some of the bituminous as well as the non-bituminous shales. Thus, it is 
clear that the ostracods themselves have not played the principal role in 
the formation of the oil shales as such. It is pertinent to mention the 
fact, however, that freshwater ostracods are known to favour a still, 
shallow water environment containing sufficient organic material for 
them to pursue their scavenging habits, and that in such an environment 
they may be found in vast swarms swimming near the surface, or 
creeping among the plants and in the mud of the lake floor. Zoological 
study has also shown that while these minute, bivalved crustaceans are 
omnivorous, they feed largely on decaying algal material. This is 
interesting, for many oil shales are now regarded as being primarily of 
algal origin. Accordingly, it is not unnatural to find ostracods abundant 
in these shales, since they apparently frequented such an environment as 
that in which the shales were formed. Their scarcity and complete 
absence from some of the oil shales, also, may possibly be correlated with 
the fact that recent freshwater ostracods are very rare in waters 
extremely high in organic material. 
