704 MEDUSAE OF THE WORLD. 



Ouoy and Gaimard give an artistic, but evidently inaccurate, figure of this medusa, and 

 they fail to describe it. Their record is only interesting in that it indicates that a Rhizostoma 

 is found in the South Atlantic. 



This form is from Table Bay, coast of South Africa, in March. It may be identical with 

 R. octopus or R. pulmo. Quoy and Gaimard's figure shows an evenly rounded, oval bell, 

 higher than a hemisphere, with smooth or finely granular surface and with numerous 

 rounded lappets, as in R. pulmo. The lower arms are apparently longer than the upper, 

 as in R. octopus, and the terminal clubs are bluntly pointed, taper from base to tip, and are 

 about as long as the upper arms. 



The colors are as in R. pulmo, but the bell and terminal clubs appear to be of a deeper 

 blue. Size ( ? ) Number of lappets ( ? ) The medusa has not been seen since the days of Ouoy 

 and Gaimard. 



Genus RHOPILEMA Haeckel, 1880. 



Rhopilema, HAECKEL, 1880, Syst. dcr Medusen, p. 596. MAAS, O., 1903, Scyphomedusen der Siboga Expedition, Monog. u, 

 p. 71. CLAUS, 1883, Organisation und Entwick. Medusen, p. 60. VON LENDENFELD, 1884, Proc. Linnean Soc. New South 

 Wales, vol. 9, p. 291. KISHINOUYE, 1890, 91, Zool. Magazine, Tokyo, vol. 2, p. 47; vol. 3, p. 53; 1899, Zoolog. Jahr- 

 biich., Abth. Syst., Bd. 12, p. 205. 



Rhizostoma (in part), VANHOFFEN, 1888, Bibliothcca Zoologica, Bd. I, Heft. 3, pp. 31, 43. 



Neclopilema, FEWKES, 1887, American Journ. Sci., ser. 3, vol. 33, p. 120. 



GENERIC CHARACTERS. 



Rhizostomata scapulata with 8 separated, 3-winged, adradial mouth-arms which bear 

 numerous filaments or club-shaped appendages. 



The central stomach gives rise to 1 6 radial-canals placed in intercommunication by a 

 network of anastomosing vessels. A ring-canal may or may not be present. 



This genus is closely related to Rhizostoma (Pilema of Haeckel), but in Rhizostoma a 

 single club-shaped appendage arises from the lower end of each of the 8 mouth-arms and 

 there are no other clubs or filaments; while in Rhopilema there are many appendages upon 

 each mouth-arm. The type species is R. rhopalophora of the Indian Ocean, and the same 

 medusa appears to have been described by Kishinouye from Japan. " Nectopilema" ot 

 Fewkes is identical with Rhopilema. 



The edible medusse of China and Japan belong to the genus Rhopilema. 



The terminal clubs upon the mouth-arms of Rhizostoma are merely the downward, mouth- 

 free extension of the axial shaft of each arm. These terminal clubs are triangular in cross- 

 section, as are the mouth-arms themselves, and they contain a continuation of the axial-canal 

 of the arm. They are not homologous with the vesicular, club-shaped mouth-filaments of 

 Rhopilema. 



Rhopilema esculenta Kishinouye. 



Rhopilema sp., KISHINOUYE, 1890, Zool. Magazine, Tokyo, vol. 2, p. 47, plate 2. 



Rhopilema esculenta, KISHINOUYE, 1891, Zool. Magazine, Tokyo, vol. 3, p. 53; 1899, Zoolog. Jahrbucher, Bd. 12, Abth. Syst., 



p. 205, taf. 13, fign. 1-5. 

 ( ?) Rhopilema rhopalophora, HAECKEL, 1880, Syst. der Medusen, p. 596. 



The umbrella is more than 450 mm. wide, about 330 mm. high when contracted, but 

 nearly hemispherical when expanded. It is about 50 mm. thick at the center, but gradually 

 becomes thin toward the margin. Exumbrella smooth, but the marginal lobes are furrowed 

 with numerous, minute, longitudinal (radial) grooves. 8 marginal sense-organs, each with 

 an exumbrella sensory pit which displays radiating furrows in its floor. In each octant of 

 the margin there are 14 to 20 oval, velar lappets between 2 very small, lanceolate, ocular 

 lappets. The ocular lappets are only about one-fourth as long and as wide as the velar lappets. 



In the subumbrella the circular muscles are well developed and unitary, and the coronal 

 furrow is not distinct. The arm-disk is very thick and prismatic, about one-third as wide as 

 the bell-diameter and somewhat longer than wide. The 4 oral pillars are quadrate and the 

 4 subgenital ostia are somewhat heart-shaped and as wide as the pillars. There is a rough, 

 prickly protuberance upon the floor of the subumbrella opposite the opening of each sub- 

 genital ostium. Altogether, therefore, there are 4 of these protuberances alternating with the 4 



