AN ICHTHYOJBDELLID PARASITIC ON SAND WHITING. 3 
About a dozen species of fish were kept in it: as well 
as the sand whiting (Sillago ciliata), there were present 
Pagrosomns auratus, Chrysophrys australis, and 
Oaranx georgianus. 
In no case were these leeches found on any fish other than 
the sand whiting. That this pond formed a favourable place 
for the development and increase of parasites was also shown 
by the fact that most of the fish, except the sand whiting, 
were infested by ectoparasitic Trematodes ; these will in du'e 
course be described by Dr. S. J. Johnston, of the Sydney 
University. 
At the beginning of February, 1914,1 had the opportunity 
of examining many hundreds of sand whiting netted by 
fishermen or caught byline in the estuarine and ocean waters 
of Wreck Bay, about 100 miles south of Port Jackson. Among 
these fish it was rare to find an individual which did not have 
from two or three to half a dozen specimens of this leech. 
I examined a large number of other species of fish netted 
along with the sand whiting, but never found them infested 
with this or any other leech. 
It was found necessary to create a new genus to contain 
this leech, which will be described under the name of 
Austrobdella translucens. 
Austrobdella gen. nov. 
Definition. — Small marine leeches with well-defined neck 
and body regions. The body cylindrical in the young, but 
much flattened in the adult. The lateral parts of the body 
below the clitellum bulging out and forming a shoulder-like 
appearance. Somite of six annuli. No pulsating vesicles 
present, their place being taken by a continuous contractile 
lacuna placed on either side outside the body musculature. 
Dorsal and ventral median lacunae present, communicating by 
segmental lacunae. Three ' pairs of pouches present in tho 
thick- walled intestine, a fourth pair being represented by :i 
flexure of the gut. Testes five pairs. Eyes one pair. 
