RHIZOSTOM^ — PHYLLORHIZA, VERSUKA. 685 



the 4 intermediate marginal lappets are broad and hlunth rounded. The 2 intermediate 



sense-organs of each octant lie in the cletts of the 2 lappets on both sides of the central fissure 



of each octant. 



When the niedusK are about 30 mm. wide the 16 intermediate sense-organs disappear 



and a new set ot 8 sense-organs develops in the middle cleft of each octant. The medusa 



now has 64 lappets and 16 marginal sense-organs. The 2 lappets on both sides of the 8 velar 



sense-organs are now double and finally divide completely. When 50 mm. wide the medusae 



lose their 8 intermediate sense-organs, and there are then 8 radial and interradial rhopalia and 



80 marginal lappets, von Lendenfeld's observations of this remarkable process of development 



await confirmation. 



Genus VERSURA Haeckel, 1880. 



Crossostoma, used for MoUusca bv Morris and Lycett, 1850. 



Crossostonia, AcAssiz, L., 1862, Conl. Nat. Hist. U. S., vol. 4, p. 155. — Maas, i903,Scyphomedusen der Siboga Exped., Monog. 



II, pp. 54, 81. 

 f^crsura-*- Crossoitoma, Haeckel, 1880, Syst. der Medusen, pp. 606, 607. 



The older species are inadequately described and we may designate F. pahnatn 

 Haeckel, from the Malay Archipelago, as the type of the genus. 



GENERIC CHARACTERS. 



Rhizostoniata triptcra with clubs and filaments upon the mouth-arms. The 4 perradial 

 canals arise directh from the stomach, but the 4 interradial canals result from the fusion of a 

 number of anastomosing vessels which arise from the interradial sides of the stomach. There 

 is no definite ring-canal, but merely a marginal network of vessels. There are no radial- 

 muscles in the subumbrella, but the ring-muscles are well-developed. 



Among characters of minor importance, the subgenital ostia are wide openings, wider 

 than the columns between them, and the sense-organs have a simple, exumbrella pit without 

 radiating furrows. At the center of the arm-disk is a prominent, raised cluster of frilled 

 mouths having filaments between them. 



The older species are so imperfectly described that it will be hopeless to attempt to 

 determine them and they had best be omitted from further consideration. For example: 

 ''^Crossostoma corolltflora" Haeckel is probably a Cotylorluza; "C diibrcuilln'' may be a Cato- 

 stylus, and "C. fronJifera" ma\' be a Cassiopea (see Haeckel, Syst. der Medusen, pp. 608, 

 609). 



Versura palmata Haeckel. 



Versura palmata, Haeckel, 18S0, Syst. der Medusen, p. 606, taf. 40, fign. 9-12. — Goette, 1886, Sitzungsber. Akad. Wissen. 

 Berlin, Jahrg. 1886, p. 836.^V,ANHbFFEN, 1888, Bibliotheca, Bd. i, Heft. 3, p. 42. — Hamann, 1881, Jena. Zeit. fur Natur- 

 wissen., Bd. 15, p. 253. 



Bell flat, shield-shaped, 60 mm. in diameter, 20 mm. high. 8 rhopalia set within very 

 shallow niches in the bell-margin. Ocular lappets very small and sharply pointed; the velar 

 lappets vary greatl\- in number, ranging from about 4 double ones to 12 in each octant. They 

 are barely discernible, being separated by very short, narrow clefts. Arm-disk about two- 

 thirds as wide as bell-radius; the 4 subgenital ostia are twice as wide as the perradial columns 

 between them. There is a unitary, narrow, cruciform subgenital cavity. The 8 mouth-arms 

 are somewhat shortef than the bell-radius. The simple upper axial shaft of each arm is not 

 quite half as long as the 3-winged lower part, which is Y-shaped in cross-section and nearly 

 as wide as long. The free edges of the Y are complexly branched and folded and bear the 

 frilled mouths. Each lamella of the mouth-arm displays 6 to 7 very deep clefts. There are 

 numerous, small, club-shaped vesicles scattered among the mouths and a larger terminal club 

 at the lower end of each arm. 



The central stomach is Maltese-cross-shaped. Canal-system of bell ( ? ) There is a 

 marginal zone of circular muscles which are only partiall\- interrupted in the 8 principal radii. 

 Centripetal to this zone is another muscular zone which is interrupted in the 8 principal 

 radii, the fibers of which are bowed outward toward the areas of interruption. Color (?) 



Haeckel records this medusa from the Mala\' Archipelago, and Goette studied specimens 

 from Zanzibar, Singapore, and Nagasaki, japan. It is distinguished only by its indistinct 

 velar lappets and the terminal club of its mouth-arms. 



