An Addition to the New South Wales Check List
of Mollusca
By J. Kerslake.
Family VENERIDAE.
Venerupis iridescens Tate (Trans. Royal Society of South Aus-
tralia. Vol. XL, 1888, p. 61, pi. ii, fig. 10).
The identification of the New South Wales species was made from
five single valves found on Collaroy Beach during the past three years.
Two of these will be presented to the Australian Museum, Sydney.
Tate has given a long and detailed description of his species from
deep water off Kangaroo Island, South Australia. However, for the
benefit of local collectors, I will recapitulate a few of the outstanding-
characteristics. The shell is similar to Venerwpis fabagella Deshayes
in outline and is approximately 15 mm. long. The colour is dirty-white,
iridescent and with a few small brown spots. It is ornamented with
about fifteen conspicuous laminae and about four concentric, rounded
threads in the interspaces. These latter are crossed by fine, close
striae.
I am indebted to Miss Hope Macpherson for permission to inspect
the South Australian specimens in the National Museum of Victoria.
Notes on Australian Shells
No. 2
By Lee Woolacott.
It is apparent that certain molluscs are migratory. Some species
travel slowly from point to point establishing colonies where condi-
tions are suitable, and over a considerable period of time appear
capable of withstanding greater differences of temperature and salinity,
thus gradually expanding their territory. Others probably drift in the
ocean currents in the larval stage, and being of a sturdy nature capable
of considerable adjustment to differing conditions, survive long enough
to breed and so form populations which may live and go on breeding
for many years, or even become permanent additions to our molluscan
fauna. Another probability is that, in the past, when ships unloaded
ballast, the eggs and partly-grown molluscs were dumped at various
places along our coast. Some species are remarkably tenacious of
life and, so long as they are able to find food which they can use,
will survive extremely varying conditions. It is very likely that the
unloading of ballast with the accompanying eggs or young is respon-
sible for the establishment of a sizable colony of Conomurex luhuanus
at Shellharbour (on the south coast of N.S.W.), a colony which has
thrived there for well over forty years.
The ebb and flow, the ever-changing pattern of population density,
and the ability of certain molluscs to survive and breed are of interest
and concern to all molluscan collectors.
It is difficult to assess the stability of various tropical molluscan
populations which are found on the coast of N.S.W., especially the
far north coast where collectors are few and information not readily
available, but in the region of the Clarence River, both north and south
of the entrance, there are to be found many tropical species which
have, undoubtedly, set up permanent colonies.
One of these, Mancinella mancinella. can be traced back for, at
least, fifteen years. Small, immature specimens have been found by
John Laseron and other collectors at Woolgoolga over a number of
years. I found one good specimen of medium size, perfectly adult in
112
BioStor
