Mar. 31, 1908. The Queensland Naturalist. 
S3 
From this it will be seen that the mineral is not a ^jure 
magnesite, the percentage of lime being above normal, 
thus probably accounting for the slight reduction in gravity 
which in normal magnesite ranges from 3 to 3.4. 
Origin . — There can be little doubt that the mineral 
has been obtained from the decomposition of the augite 
and olivine of the basalt, chiefly from the latter, which is 
more readily decomposed. The lime has a probable source 
in the Labradorite feslpar of the same rock. The carbonic 
acid has been derived from the decomposition of vegetation, 
and this has had the effect of keeping the iron in the ferrous 
condition. The sesquioxide of alumina is quite free, there 
being no silica whatever in the specimens analysed. 
A peculiar characteristic of the specimens in the occur- 
rence on the outer surface of a pseudo-columnar structure. 
A delicate and very regular hexagonal pattern (the width 
of the hexagons varying from .5 to 1 centimetre) covers 
the whole outer surface, but the marking fades in a very 
short distance. It is hard to account for such a structure, 
as one would expect that if shrinkage subsequent to deposition 
had been the cause, the cracks would penetrate into the 
mineral. The usual cavities so commonly found in Dolo- 
mite occur to a small degree only in the specimens. ,Mag- 
nesite belongs to the Rhombohedral group of the Hexagonal 
system, but when cr^^stallised it is found in rhomb;^ crwing 
to its perfect cleavage. The hexagonal cracks mav pos- 
sibly be due ,to incipient crystallisation 
NOTES OX ROTIFERA. 
By W. R. Colledge. 
1. I have found a somewhat rare Rotifer in some of the 
pools lately, viz., “ Pedalion mirum.” Thirty years ago 
Dr. G. Thorpe. R-X"., noticed it at Dunk Island, Kennedy 
Bay. But I do not know that it has been seen nearer the 
metropolis until I found the specimens in the contents of my 
net. It is only the eighty -fifth part of an inch in lengtli, and 
of very peculiar shape. The body is like a truncated ca*ne. It 
possesses six limbs, but no two of them are alike, tlnmgli 
all terminate in broad fan-like setae. Its ordinary mode 
of locomotion is to swim by means of the cilia on tiie wide 
coronary wreath, but it fre<^uently takes to skipping 
This IS eftected by the sudden contraction of some of the 
forty-two striated muscles attached to its various orimns 
The effect is to project the creature often a hundred times 
its length in the water, and so escape from its eneinies. 
The possession of jointed limbs renders it an tjbject 
of interest, as it brings the Rotifers near to the Crustacea' 
