Had
travelled, during the latter part of the stage, over well grassed, openly
timbered flats. The ranges on the left side of the river extended several
miles farther, but gradually sunk into a level country.
[Note 1: The following description of the fossiliferous limestone of the
Burdekin, was communicated to me by the Rev. W. B. Clarke, F.G.S.
This rock consists of a semi-crystalline, greyish-brown marble, very like
some varieties of Wenlock limestone.
The most conspicuous fossil is a coral, which appears to belong to
the family of Cyathophyllidae. The genus is perhaps new; but this the
want of specimens with which to compare it, does not allow me the
means of verifying. It may, however, be classed provisionally as
Cyathophyllum, to which in many respects it bears a great resemblance;
and although it is somewhat contrary to the present rules of
classification to assign a specific name from a person, yet, in
order to do honour to my friend on account of his skill, diligence, and
zeal as a naturalist, as well as a traveller, and as this is the first
fossil coral brought away by the first explorer of the region in which
its habitat is found, I venture to name it C. Leichhardti.
The description may be given as follows:
Cells concavely cylindrical, not dichotomous (thus distinguished from
Caryophyllia), grouped but separate, laterally if at all proliferous.
Corallum beautifully stellular, formed by 30-35 slightly spirally-curving
or regular radiating lamellae, which meet in a central point or overlap
on a latitudinal axial line, and are divided by rectangular or outwardly
convex and upwardly oblique dissepiments, which become, occasionally,
indistinct or obsolete near the centre, thus not assuming the usual
characteristic of Cyathophyllum, but rather one of Strombodes.
Surface longitudinally striated, the cellular structure being hidden
in calcareous spar; the striae formed by the coalescing lamellae,
which, at the extremities, seem to be occasionally denticulated, owing to
the matrix interrupting their passage to the edge. This resembles what
takes place in some Astraeidae.
The interior has more the features of Acervularia than Cyathophyllum;
but there are patches of broken transverse septa in the rock which
exhibit the features of the latter.
Associated with this is a branching coral, a fragment of which, in
a small angle of one of the surfaces of the stone, exhibits the characters
of Favosites. There are also traces of casts of Spirifers, one of which is
near to S. Pisum of the Wenlock rocks. (Silur. Syst. pl. xiii. f. 9).
The description here given is deduced from the natural appearances
under the lens, and not from artificial or regular sections. But
the specimen admits of a partial substitute for this; for the surface
is worn down and roughly polished, as is the case with all the exposed
surfaces of ancient limestones in Australia; the result probably of the
acidulous properties of rain water, or of the atmosphere, which, in a
tropical climate, where violent showers alternate with great drought, is
capable of producing various sensible changes in rocks in a long series
of ages.
