650 



MEDUSA OF THE WORLD. 



bell-radius give off 8 to 12 main branches each, which also branch in a tree-like manner. 

 Numerous large club-shaped vesicles between the mouths, some half as long as bell-radius. 



Bell yellowish, rust\-brovvn, lighter in the center. Radial streaks reddish-brown. There 

 are 2 white, halt-moon-shaped spots over each rhopalium. Upper surfaces ot mouth-arms 

 light-yellow. Mouths dark rusty-yellow. Vesicles white. 



Found at Ualan, Caroline Islands, tropical Pacific. 



Cassiopea ndrosia Agassiz and Mayer. 



Casslopea ndrosia, .\gassiz and Mayf.r, 1899, Bull. Museum Comp. Zool. at Harvard College, vol. 32, p. 175, plate 14, figs. 



45. 46- 

 Cassioptja mertemii var. ndrosia, Maas, 1903, Scyphomedusen der Siboga Exped., Monog. 11, pp. 40, 43. 



Bell 50 mm. in diameter with a shallow concavity at the center of the e.xumbrella, similar 

 to that of C. xamachana. Rhopalia variable in number, 18 to 22. Marginal lappets very 

 indistinct but there are 2 velar flanked by 2 ocular lappets in each paramere. Mouth-arms 

 cylindrical, 1. 5 times as long as bell-radius, and branched in a tree-like manner. Each arm 

 gives off 6 to 12 main side branches. There are numerous small, flattened, expanded leaf- 

 shaped vesicles between the mouths, most numerous at center of arm-disk. No ribbon- 

 shaped filaments. 4 small, round, subgenital ostia. 4 separate genital sacs. 



General color of bell grayish-brown, with bluish, inter-rhopalar, radiating streaks and 

 white radiations in the subumbrella in the rhopalar radii. A large, spearhead-shaped white 

 spot with its pointed end outward is found near the margin of the exumbrella above each 

 sense-organ; there are also 4 small, radially elongated, white spots near the margin in each 

 paramere — one above each of the rudimentary lappets. The aboral surfaces of the mouth- 

 arms are grayish-white, the mouths deep brown, and the vesicles olive-green. 



Found upon muddy bottoms in Suva Harbor and at Komo Island, Fiji Islands, South 

 Pacific, in November. 



C. ndrosia lacks the large vesicles of C. mertensii and has an aboral exumbrella concavity, 

 whereas the bell of 6'. mertensii as, apparently, evenly rounded. It is most closely related to 

 C. xamachana ot the West Indies, and resembles one of its color varieties, but lacks the ribbon- 

 like filaments of C. xamachana. 



RHIZOSTOMATA DICHOTOMA Vanhoffen 1888. 



Rhizostomala dichotoma, Vanhoffen, 1888, Bibliotheca Zoologica, Bd. i. Heft. 3, p. 39. — Maas, 1903, Scyphomedusen der 



Siboga Expedition., Monog. I j, p. 31. 

 Chaunoslomidit+Ce[>heid^,C\jKV!., 1883, Organisation und Entwick. Medusen, Leipzig. — von Lendenfeld, 1888, Zeit. fiir 



wisscn. Zool., Bd. 47, p. 211. 

 Radiomyaria, Maas, 1903, Scyphomedusen der Siboga Exped., Monog. 11, p. 89; 1907, Ergeb. und Fort. Zool.,Bd. I, p. 201. 



CHARACTERS OF THE GROUP. 



8 separate mouth-arms the lower ends of each one of which gives rise to 2 expanded, 

 leaf-like side-walls, or lateral membranes, the outer edges of which give rise to secondary 

 branches and bear the frilled mouths. Thus each arm is V-shaped in cross-section ffig. 404). 



Fk;. 404. — Diagrammatic representation of the shape and position of the mouth-arms in the 

 Rhizostomala dichotoma. The figure on the right hand shows a section of one of the 

 moulh-arms. Tlic middle figure is an oral view of the bell. 



