4 
and crannies. At certain times* they appear in considerable 
numbers, and occasionally I have lifted stones in Port Jackson, 
each one of which had at least a dozen attached to it. At times 
I have collected this Leptoplana in close proximity to oysters, and 
knowing the carnivorous habits of its terrestrial relatives, the 
land Planarian worms, have considered it likely that the oysters 
might be at times subject to attack, though positive evidence until 
recently has not been forthcoming. 
Before proceeding any further, I might mention that the colors 
of this organism are as follows :— 
Upper surface, light brownish ground, mottled all over with 
darker brown, and darkest towards the central portion. The lighter 
ground color often shows as radiating streaks. The lower surface 
is creamy yellow, or grayish, the highly-branched intestinal tract 
showing up clearly through the skin. When freshly taken from the 
water the whole surface glistens, and is covered with a slimy 
mucus. 
A few years ago I found that this worm was known to a few of 
the oyster farmers of George’s River, who had repeatedly observed 
it amongst oysters on various leases, and that they distinguished it 
under the name of “ Wafer.” As this name appears to be fairly 
suitable, I propose for the future to use it in speaking of this 
worm. Though, as I say, the Wafer has been known to certain 
lessees, no definite connection between the oyster and this worm 
has been shown to exist, and no satisfactory evidence has been 
brought forward to show that the latter was to be added to 
the already long list of oyster pests. However, in the light of 
recent evidence, I think it will be found that this is a pest, that it 
is at times to be seriously reckoned with, and that it will be found 
to be fairly widespread in our oyster-producing waters. 
At the end of July this year (1907), Mr. J. W. Swainson, of 
George’s River, handed to me for determination a number of 
examples of the “ Wafer,” which, he said, was very plentiful on his 
* Judging by my present data, they appear to be most plentiful during dry weather (and 
particularly while mild or high temperatures prevail) when the water of our estuaries is of greater 
density. 
