17 
the estuary), the tow-net reveals the presence of the larvae of our 
common prawns belonging to the genus Penaeus or Metapenaeus. 
These larvae are particularly interesting, for it is extremely rare 
for the Decapod Crustacea to be hatched from the eggs as Nauplii. 
It is known in several cases in the group Penaeidae. We have ob- 
tained the nauplius larvae of the Swan River species, and it would 
appear as if the complete development could be worked out quite 
easily from a complete series of plankton catches. 
Our Swan River and Fremantle Harbour catches have also 
indicated the presence of Phoronis in our waters. The adults have 
never yet been recorded, but must occur, for we have captured 
Actinotrocha larvae in the plankton. Our Swan River estuary 
plankton and also that collected between Garden Island and Fre- 
mantle seems at times to be particularly rich in Tintinnidae. Great 
swarms occur, and on one occasion the presence of these organisms 
was found to be associated with a line display of so-called phos- 
phorescence. Amongst the phytoplanktonie forms the well known 
genera Chaetoceros, Rhizosolenia, Ceratiurn and Peridinium abound, 
but it is impossible to work out the species with the literature at 
our disposal. 
The plankton work remains in fact untouched. The Hamburg 
Expedition must have made very extensive collections, but up to 
date nothing has been published except a small paper by Lohmann 
on pelagic Tunicata. 
Amongst larger planktonic organisms we can record Porpita, 
Physalia, and Beroe. The latter genus occurred in myriads in Bun- 
bury Harbour in May, 1913. 
Mollusca. 
The Mollusca are probably as well known as any marine group 
from the Western Coast of Australia. ,1 should like to add a few 
words upon this group, which perhaps has received more of my 
notice in the past than any other Phylum. Two groups of molluscs 
are of outstanding importance, economically, on our coasts, and in 
very different ways. One group, that of the shipworms belonging 
to the genus Nausithoria, is a pest, causing the destruction of 
wooden piles at Bunbury, Fremantle, and other ports to the extent 
of thousands of pounds sterling. The other group is of value, and 
includes the species eagerly sought after for pearls and pearl shell. 
The common species of “shipworms” (the best known genus is 
Teredo), found at Fremantle are Nausithoria saulii and Nausithoria 
thoracites, the first-named being recorded here for the first time from 
West Australia. Both species attack; the jarrah piles. The life 
history and anatomy are fairly well known, and the Biology De- 
partment of the University has made some investigations into the 
