298 



DISCOVERY REPORTS 



The earliest stages observed have no remnants of the apical canal which has con- 

 nected the young medusa with its hydroid, and may already be somewhat advanced in 

 development from the moment of liberation. The European species, Phialella quadrata, 

 begins its free-swimming life with four perradial tentacles and four marginal statocysts, 

 each containing two statoliths. In the next stage there are eight tentacles and eight 

 statocysts. The youngest specimens of Ph. folklandica all have eight adradial statocysts 

 and four perradial tentacles, and the four interradial tentacles are just beginning to 

 develop and are visible as four minute bulbs. When the medusa is i mm. in diameter 

 there are, as a rule, eight tentacles, four large perradial and four smaller interradial. 

 The next series of eight tentacles are developed between the perradial tentacles and the 

 adradial statocysts, close beside the latter ; they are followed by another series of eight 

 tentacles which appear on either side of the interradial ones, and after them come 

 eight tentacles flanking the perradial. From this time the addition of new tentacles 

 becomes less regular (diagram. Fig. i). 



The rate of development of the tentacles in proportion to the size of the umbrella 

 shows some variation, but the numbers most frequently found are as follows: 



The marginal vesicles or statocysts are large and globular in shape (Plate XVII, fig. 4). 

 As some of the specimens are preserved in alcohol the number of statoliths may be 

 stated ; in the intermediate stages each statocyst contains three to four statoliths, but in 

 the early stages there are only two. The vesicle is situated on a broad, cushion-like 

 bulb. 



The velum is well developed, and in the young stages it is remarkably broad. 



As mentioned above, the medusa recorded by Vanhoffen (191 1) as Ph. falklandica 

 from Kerguelen Island and the surrounding area really belongs to CosmetireUa davisi. It 

 seems probable, on the other hand, that the specimens described by Vanhoffen in his 

 paper on the medusae collected by the 'Vettor Pisani' (Vanhoffen, 19126) under the 

 name of Phialella falklandica were correctly identified ; they were found in various 

 localities on the coasts of South America : Punta Arenas and Fortescu in the Strait of 

 Magellan, Valparaiso in Chile, and Callao in Peru. The excellent description and 

 figures of a Phialella from the Auckland and Campbell Islands south of New Zealand 



