HYDROMEDUSAE 317 



This genus, which is named after Mr Rupert Vallentin, has a well-marked character 

 in the presence of four large perradial tentacles with a terminal adhesive disk. Without 

 these modified tentacles the medusa would have all the generic characters of an 

 Aglauropsis. The genus only comprises one species. 



Vallentinia falklandica Browne (Plate XVIII, figs. 17-19; Plate XIX, figs. 6, 7). 



Vallentinia falklandica Browne, 1902, p. 284. 

 Vallentinia falklandica Mayer, 1904, p. 20. 

 Vallentinia falklandica Browne, 1904, p. 738. 

 Vallentinia falklandica Maas, 1906, p. 19. 

 Vallentinia falklandica Mayer, 1910, p. 352. 



Specific characters. Adult (Plate XVIII, fig. 17): Umbrella bell-shaped, about i| 

 times as high as broad. Stomach short, about one-third the length of the umbrella cavity, 

 not situated on a peduncle. Mouth with four short simple lips, the mouth rim provided 

 with nematocysts. Radial canals four. Gonads situated on the radial canals in the upper 

 half of the umbrella cavity, a little way below the stomach, oval and sac-like. Tentacles 

 four large perradial with scattered nematocysts and with terminal adhesive disks, and 

 twenty-four (six in each quadrant evenly distributed) with transverse bands of nemato- 

 cysts. Sixteen vesicular statocysts enclosed inside the margin of the umbrella, each 

 with a single statolith. Velum very broad. Colour: Gonads and stomach pale yellow 

 (in formalin). Size: Umbrella 3 mm. in height and 2 mm. in width. 



In the first collection there was only a solitary specimen of this most interesting 

 medusa, taken on 11 December 1898 in Sparrow Cove in Port William Bay, which 

 is just outside Stanley Harbour. The third collection contains a specimen, taken on 

 8 November 1909, and ten specimens taken on 4 December 1909 (exact localities not 

 stated) ; they are somewhat smaller than the type specimen, being 2-2J mm. in height 

 and i|-2 mm. in width (Plate XIX, figs. 6, 7). 



The perradial tentacles with adhesive disks indicate that the medusa must have a 

 special use for them, and presumably it has adapted itself for living amongst the kelp, 

 which forms marine forests round the shores of the Falklands. The tentacles would be 

 used for clinging on to the branches of the kelp, and the medusa's mode of life would 

 resemble that of Cladonema, which lives amongst the Zostera on the British coasts. 



As long as this medusa was only known from the original brief description (Browne, 

 1902), its specific value has been doubted. Maas (1906) designates it as " Larvenform 

 von umbestimmter Zugehorigheit ", and Mayer (1910) suspects that it may prove to be 

 an immature stage of some Olindias. As a matter of fact, it is a well-defined species, 

 representing a well-marked genus, and quite distinct from Olindias and from any other 

 genus of the Olindiidae. 



In the exumbrella there are several scattered nematocysts. The walls of the umbrella 

 are moderately thick in all parts ; the umbrella cavity is somewhat quadrangular in trans- 

 verse section. 



The manubrium is not on a peduncle ; it is small, in most specimens it is cylindrical 

 or prismatic, in one specimen it is barrel-shaped (Plate XIX, fig. 6), somewhat con- 



