66 



THE SCYPHOMEDUSAE 



The tube of the manubrium leads into a short gasttic cavity; 

 from this four broad shallow perradial canals or pouches, separated 

 by narrow interradial mesenteries, lead to the circular canal at the 

 edge of the bell. This canal is further subdivided by fusion of its 

 exumbral and subumbral walls into pouches, eight (Charybdaea) 

 or sixteen (Chirodropus) in number ; from these lead the canals 

 of the tentacles and velarium. The mesenteries are traversed 

 by an endoderm lamella, and carry interradial phacellae at their 



Fig. 5n. 



1. Horizontal section through the unibrpUa and 

 iiiauubriuni of Charylidaca marsiipialii (nio<lilie(l 

 from Glaus); Mn, niamibrium ; SS, side ridge (per- 

 I'adial) ; CJi, corner ridges, separated by t'(r', the 

 interradial comer groove ; Ge, the genital lamellae 

 in section, projecting from the interradial angles on 

 each side into i'E, the radial canals of the umbrella ; 

 .^'f, the subumbral space. 2. Vertical sections of 

 (haryliilftai marsupialis, to the left in the plane of an 

 interradius, to the right in the plane of a perradius ; 

 Ma, manubrium ; EAr, gastric cavity ; C,h, gastral fila- 

 ments (jihdirlltw) ; CV;, corner groove ; SH, side ridge ; 

 EnL, endodenu lamella (line of concrescence of the 

 walls of the enteric cavity of the umbrella, whereby its 

 single chamber is broken up into four pouches); Ge, 

 line of attiichment of a genital band ; El', circular 

 canal, giving origin to TCa, the tentacular canal ; Ve, 

 velarium ; Fr, frenum of the velum ; T<; tentaculocyst. 

 (From Laiikester.) 



aboral ends. In a few cases eight adradial arms canying 

 digitate filaments grow out from the exumbral body wall, 

 and hang free in the radial canals (Chirodropus). As in Hali- 

 clystus, the fjenerative organs grow out from the sides of the in- 

 terradial mesenteries, and form leaf-shaped projections into the 

 radial canals. 



Practically nothing is known of the development of thi.s 

 group. 



