HYDROMEDUSAE 275 



Description of the type specimen (Plate XIV, figs. 3-4). Umbrella circular, about 

 twice as broad as high. Stomach tube conical and small. Mouth without lips, a plain 

 round margin. Gonads occupying the whole of the upper part of the umbrella, above 

 and around the stomach. Tentacles twenty-four, divided into two branches: the upper 

 branch with clusters of nematocysts, the lower with a terminal adhesive disk. An 

 ocellus on the extreme margin of the umbrella, opposite each tentacle. Colour: "The 

 whole medusa was pure white in colour, with the exception of the bases of the tentacles 

 which were tinged with red" (note on the living specimen by R. Vallentin). Ocelli 

 reddish brown (in formalin). Size of living specimen: umbrella 3 mm. in width and 

 2 mm. in height (according to Vallentin). 



A single specimen was found on a frond of Macrocystis, commonly called kelp, in 

 Stanley Harbour, about i fathom below the surface on 6 December 1898. 



The specimen in formalin is not quite so large as the dimensions given by 

 Mr Vallentin, and the colour is no longer pure white, but rather pale yellow. The 

 clusters of nematocysts are decidedly yellow. The tentacles are figured somewhat 

 diagrammatically, owing to their distorted positions in the preserved specimen, which 

 has only twenty-one tentacles. A vacant space suggested that the margin of the 

 umbrella has been damaged and that at least two tentacles were missing. Two tentacles 

 were added in the figure to fill up this gap and to give a more natural appearance to the 

 medusa. After the drawing was finished, it was found that Mr Vallentin had carefully 

 examined this medusa whilst alive and had made some notes upon it. He records that 

 the medusa has twenty-four tentacles, so that the figure is one short in number. The 

 arm of the tentacle bearing the nematocysts is uppermost, and has usually two or three 

 clusters on the upper side and occasionally a cluster on the lower side ; there is always a 

 terminal cluster forming a knob (Plate XV, fig. 4). The number of clusters varies from 

 one to three, exclusive of the terminal cluster. The size of the clusters indicates that at 

 first only one cluster is present, the terminal one, and the other ones appear later, the 

 oldest being nearest the terminal cluster. The lower branch or arm with the adhesive 

 disk is without nematocysts. 



There are also two minute bulbs on the margin of the umbrella, nearly opposite each 

 other. These bulbs may be either the commencement of other tentacles, or rudimentary 

 medusa buds. The radial canals are quite invisible owing to the opaqueness of the body. 



Note by R. Vallentin : " The medusa is able to progress through the water at a fairly 

 respectable pace by means of its tentacles which open and close simultaneously. It 

 swims very much like Gonactinia prolifera, the budding anemone." 



On 2 December 1901 Mr Vallentin collected some more specimens of this medusa. 

 In his notes he writes as follows: " Colour of living animal on dark background: body, 

 gonads, stomach, and arms pellucid. Eyes reddish brown. Diameter of living animal 

 when walking 5 mm. including tentacles, body i mm. excluding tentacles. No medusa- 

 buds observed on any of the specimens. The animal, when walking, keeps the hollow 

 tentacles waving about in the water, the tentacles with suckers being closely applied to 

 the side of the jar of sea-water in which it is confined. These ambulatory gonozooids 



