Haddon — On Parasitic Larva of Halcampa. 477 



were usually attached to the stomach on the sub-umbrella (PL XI., 

 figs. 1, 2) of different species of Leptomedusse. Occasionally they 

 -adhered to the margin of the disc. With a little care they can be 

 kept alive some time, and will feed on small pieces of meat when 

 medusae are not to be had. 



When first obtained some specimens measured a little under 

 3 mm. in length, and one grew to about 5 mm. in length. 



The body was sub-conical in form, the column not being dis - 

 tinctly divided into the three regions (capitulum, scapus, and 

 physa) so characteristic of the adult. The middle portion was 

 especially corrugated, and indented at the insertion of the mesen- 

 teries. The body could be slowly lengthened or contracted ; it 

 was uniformly clothed with small cilia. There were only eight 

 short tentacles. At first they were very short, but afterwards they 

 grew relatively longer. 



The Medusa appears to be but little incommoded by the 

 parasite ; but it probably succumbs in time to its guests. In its 

 ordinary condition the Anemone sinks in the water when taken 

 from the Medusa ; but it can extrude its mesenteries through its 

 mouth for a considerable distance (PI. XI, fig. 5) . These enable 

 it to float at the surface of the water, and, at the same time, to 

 attach itself to passing Medusae. This is probably the manner by 

 which it secures a continual supply of food. 



They had a uniform yellowish flesh- colour, with eight rudi- 

 mentary tentacles. The tentacles grew longer, and were tinged 

 with brown and yellowish white. The disc also became variegated 

 with brown, and the body translucent, revealing the yellow oeso- 

 phagus. At the last observed stage the body was almost colour- 

 less — the oesophagus yellow, the capitulum possessed a pair of 

 cream-coloured spots below each tentacle, and the insertion of the 

 mesenteries were of the same colour-— the eight tentacles had on their 

 oral surface two transverse bars of white at the base, and a single 

 bar half-way along their length. Above this was a large brown 

 spot, and a pair below it ; and above the basal lines, between the 

 two brown spots, is a small white one. The disc was prominent, 

 with white radial lines, the areas being brown, finally speckled with 

 white, each having prominent white spots at the mouth. 



Although there were eight tentacles there were twelve mesen- 

 teries. The tentacles were arranged in two groups of three, and a 



