166 



COELEXTERATA. 



Sub-order 3. CUBOMEDUSAE (Marsupialida}. 



FIG. 137. The apical half of aCharybdea 

 divided transversely, seen from the 

 sub-umbrella side. The four oral 

 arms are visible. Oe ovaries on the 

 four septa ; Ost ostia of the gastric 

 pouches ; Gf gastric filaments ; S 

 septa. 



With quadrangular umbrella (Fig. 136), 

 4 perradial rhopalia (with otoliths and 

 eyes), 4 interradial marginal tentacles, 

 4 perradial gastric pouches, separated by 

 long and narrow interradial septa. Gonada 

 as 4 pairs of broad plates fastened by one 

 edge to the radial septa (Fig. 137), and 

 projecting into the pouches. With a 

 smooth - edged velarium containing pro- 

 longations of the gastrovascular system. 

 With a nerve ring on the sub -umbrella 

 side of the edge of the bell, having a zig- 

 zag course. 



Fam. 5. Charybdeidae. Procharagma 

 H.; Procharybdis H. ; Charybdca Per. and 

 Les. ; Tamoya F. Miiller. 



Fam. 6. Chirodropidae. C'hiropsalmus 

 L. Ag. ; Chirodropus H. 



Order 2. EPHYRONINAE. OCTOMERALIA. DISCOMEDUSAE. 



Acalephae with 8 or more rhopalia (sense tentacles) (4 per- and 

 4 interradial, and often several accessory}. Stomach with 8, 16, 32, 

 or more radial pockets or canals. Gonads sub-gastral (in ventral wall 

 of central stomach). Umbrella flat, generally discoidal. Larval form 

 Ephyra. 



The Ephyroninae can at once be distinguished from the Scypho- 

 medusae by the discoidal lobed umbrella, and usually by the large 

 size of the oral tentacles. The lobes of the umbrella, however much 

 they may differ in detail, can always be reduced to the eight pairs of 

 lobes of the Ephyra (Fig. 131), which, as the promorph of the 

 Ephyroninae, presents most clearly the 8-rayed symmetry character- 

 istic of the group. 



The gonads have the form of horse-shoe shaped frills (Fig. 130), 

 and project into the widely open subgenital pits. The germinal 

 epithelium, which is always embedded in the gelatinous substance 

 of the umbrella, is covered with an endodermal layer. Development 

 takes place by alternation of generations. In rare cases (Pelagia) 

 the development is simplified, and the larva passes directly into the 

 Ephyra, missing out the attached Scyphistoma and Strobila stage. 



The gastrovascular system may be pouch-like or canalicular. In 

 Aurelia (Fig. 130), in which it is canalicular, the eight primary radial 

 canals (i.e., the four perradial and four interradial) are branched, while 



