14 MEDUSA OF THE WORLD. 



Subfamily No. i, RHOPALONEMINjE. 



Trachynemidae in which the stomach lacks a peduncle. 

 RHOPALONEMA, Gegenbaur, iS^6=Trachynema (young medusa), Gegenbaur, 1854 



= Trachynema + Rhopalonema + Marmanema, Haeckel, 1879. 



With eight well-developed radial tentacles, and eight or more small cirrus-like or club- 

 shaped interradial tentacles. All tentacles arise in a single row. Eight gonads 

 localized on the eight radial-canals. Four lips. 

 SMINTHEA, Gegenbaur, 1856. 



Similar to Rhopalonema, but with only eight tentacles, one at the foot of each of the 



eight radial-canals. 



HOMCEONEMA, Maas, i8g3 = Colobonema, Vanhoffen, igo2 = lsonema (in part), Maas, 1906. 

 Similar to Rhopalonema, but the tentacles are all of one sort. No small club-shaped or 



cirrus-like tentacles. Four lips. 

 PANTACHOGON, Maas, 1893 (sens. ampl.). 



Gonads not localized as in Homceonema and Rhopalonema, but developed diffusely over 



the radial-canals. Four lips. 

 HALICREAS, Fewkes, i$82 = Halicreas + Haliscera, Vanhoffen, 1902 



= Isonema (in part), Maas, 1906. 



The mouth is a simple round opening, without four lips. (In all known species the 

 radial-canals and ring-canals are very broad and flat.) Wart-like protuberances 

 may be present upon the sides of the exumbrella. Radial tentacles large, interradial, 

 small. Tentacles arise in a single row. 

 BOTRYNEMA, Browne, 1908. 



Similar to Halicreas, but the tentacles are grouped in linear clusters in a single row 



around the bell-margin. 

 CROSSOTA, Vanhoffen, 1902. 



The tentacles arise in several rows from the bell-margin. Mouth with four lips. 



Subfamily No. 2, AGLAURINjE. 



Stomach mounted upon a peduncle. 

 AGLAURA, Peron and Lesueur, 1809. 



Eight gonads upon the peduncle above the stomach. Sexes separate. Development direct. 

 AGLAmHA = /fglantha + 4glisi:ra, Haeckel, 1879. 



Eight gonads upon the subumbrella, or at the turning points of the eight radial-canals 



between the peduncle and the subumbrella. Sexes separate. 

 AMPHOGONA, Browne, 1904. 



Similar to Aglantha, but medusa is bisexual, four of gonads being male, and four female. 

 STAURAGLAURA, Haeckel, 1879. 



Four gonads, one upon each alternate radial-canal. 

 PERSA, McCrady, 1857. 



Two gonads on two of the radial-canals, 180 apart. The six other radial-canals are sterile. 



Family No. 6, GERYONIDjE. 



Trachymedusae with four or six radial-canals upon which the flat, expanded, leaf-like 

 gonads are developed. Stomach mounted upon a gelatinous peduncle. The ring-canal 

 gives rise to blindly-ending centripetal canals. 

 LIRIOPE, Lesson, i%^ = Linantha -\-Lirwpc + Glossocodon -\-Glossoconus, Haeckel, 1879. 



Four radial-canals. Four gonads. Four lips. With four primitive, solid, radial, and four 

 solid interradial, and four hollow, flexible, radially-placed tentacles; all twelve of 

 which may be found upon the medusa at one and the same time. Development 

 direct through a free-floating, actinula-like larva. 

 GERYONIA, Peron and Lesueur, i8og = Geryones + Geryonia + Carmaris 



+ Carmarina, Haeckel, 1879. 

 Similar to Liriope, but with six radial-canals, six gonads, six lips, etc.; instead of four. 



