222 
C. BAPHAM, 
respect — that they live either on the exterior of their host r 
or in the gut which opens freely by a mouth. The larvae of 
P. hilli, however, live for a considerable period in the radial 
canals of a Rhizostome, from which they can only escape by 
perforating the body-wall of their host. This host is a large 
form, Crambessa mosaica, which is found in the land- 
locked harbours along the coast of New South Wales. This 
medusa is frequently found in large numbers, possibly brought 
together by currents and tidal action. At other times it is 
widely scattered. At all times it forms a very characteristic 
faunal element of the various inlets. So far as I can ascer- 
tain, it passes through its life-history in these waters. 
Peach ia hi lli, the adult form of these larvae, is found 
in Broken Bay, and was described by Miss Wilsmore (3) in 
1911. She also described a free-living larval form, the 
internal anatomy of which showed that it was the larva of 
P. hilli. 
The larvae which are found parasitic correspond in their 
older stages with the larva found free-living, and so link up 
the medusopliilous forms with the adult. 
Character and Occurrence of Larvae. 
The larvae are found in various parts of the large radial 
canals adhering to the ex-umbrella wall of the gut, excepting 
when they are making their way out of their host. I found 
them at various stages of development from 5 mm. to 40 mm- 
long. They occur in about every tenth medusa examined 
during the months of September and October, but by January 
it is rare to find them. 
In October they were noticed in the act of escaping from 
their host, going through a hole, regular in outline, made in 
the sub-umbrella wall of the gut, near its periphery. I have 
found larvae lying free in the gut, But near a hole, others 
actually filling up such a hole, with their oesophageal end 
protruding, and yet others, having effected their escape,, 
adhering to the tentacles of their host. This latter condition 
