180 



ZOOLOGY 



SECT. 



separated from one another by narrow inter-radial septa or partitions (mesen- 

 teries) placed at the four corners. These pouches are equivalent to wide radial 

 canals, and the partitions between them to a poorly developed endoderm lamella 

 (end. lam. ). At the margin of the umbrella the pouches communicate with one 

 another by apertures in the septa, so that a kind of circular canal is produced 

 (circ. c.), which is divided into chambers by the mesenteries. Near the 



Fia. 135. Charybdaea marsupialis. A, side view of the entire animal ; B, vertical section 

 passing on the left side through an inter-radius, on the right through a per-radius ; 

 G, transverse section, circ. c. circular canal ; end. lam. endoderm lamella ; end. lam', its 

 prolongation into the velarium ; g.f. gastric filaments ; gon. gonad ; gon'. septum separa- 

 ting gonads ; 1. lappet ; mnb. man'ubrium ; rad. p. radial pouch ; t. tentacle ; tc. tenta- 

 culocyst ; vl. velarium. (After Claus, somewhat altered.) 



junction of the gastric pouches with the stomach are the usual four groups of 

 gastric filaments (g. f. ). 



The gonads (gon.) are four pairs of narrow plate-like organs, attached one 

 along each side of each inter-radial septum. The nervous system takes the 

 form of a sinuous nerve-ring round the margin of the bell, bearing a distinct 

 group of nerve-cells at the base of each tentaculocyst and tentacle. The 



