IV 



PHYLUM CCELENTERATi 



181 



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

 (/.) and four tentaculocysts ((c) 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 hpm conspicuous 

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

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



'adjt 



Fig. 134.— Chary bdaea 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 ; e.nil. lam. endoderm lamelln. ; end. lam', its pro- 

 longation into the velarium; g.f. gastric filaments; gon. gonad; yon', septum sepaiHtinpr 

 gonads ; I. lappet ; mnb. manubrium ; rati. 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 shell (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 



