PHYLUM CCELENTERAT^ 



181 



As in the lower Coronata, the margin of the umbrella bears four tentacles 

 (f.} and four tentaculocysts (tc.) but the position of these organs is reversed, the 

 tentaculocysts being per-radial, the tentacles inter-radial. The tentaculocysts 

 are set in deep marginal notches, and the tentacles spring from conspicuous 

 gelatinous lobes (/.), which probably answer to the pedal lobes of the preceding 

 order. These pedal lobes sometimes bear a number of supplementary tentacles. 



FIG. 134. Cnarybdaea 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 ; 

 C, transverse section, circ. c. circular canal : <>></. lain, endoderm lamella ; tn<L lam', its pro- 

 longation into the velarium ; g. f. gastric filaments ; gon. gonad ; gori. septum separating 

 gonads ; i. lappet; mnb. manubrium ; rod. p. radial pouch; t. tentacle; tc. tentaculocyst ; 

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



The margin of the umbrella is produced, in most cases but not in all, into a 

 horizontal shelf (rf.), resembling the velum of the hydroid Medusze, but differing 

 from it in containing a series of branched vessels (end. lam'.) continuous with the 

 canal-system and of course lined with endoderm. In the Hydrozoa, it will be 

 remembered, the velum is formed simply of a double layer of ectoderm with a 



