PHYLUM CCELENTBRATi 



181 



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

 (t.) 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 (L), which probablj' answer to the pedal lobes of the preceding 

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



ffon. 



end lam 



circ^ 



•culp 



Fig. 134.— Charybdsea xuarsupialis ■ A, aide view of tlie entire animal ; B, vertical section 

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

 C, transverse section, circ. c. circular canal ; ':ti'/. lam. endoderm lamell:'. ; 'riuK lam', iia pro- 

 longation into the velarium ; g. f. gastric filaments ; gon. gonad ; gon'. septum sepaiatin^ 

 gonads ; I. lappet ; rnnb. manubrium ; rad. p. radial pouch ; t. tenfeicle ; tc. tentaculocyst ; 

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



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

 horizontal shelf (vL), resembling the velum of the hydroid Medusae, 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 



