102 



INVERTEBRATE MORPHOLOGY. 



appearance, which, combined with irregularities of growth of 

 the coeleuteron, give its peripheral portions an irregular out- 

 line (Cyanea), or convert them into a series of anastomosing 

 canals, e.g. Aurelia. The margin of the bell is usually more 

 or less lobed, eight of these lobes being especially distinct 

 and carrying the sense-organs, the intervals between them 

 being usually occupied by the secondary tentacles when these 

 are present. The depressions of the subumbrellar surface are 

 no longer deep funnels, but form rather shallow subgenital 



FIG. 54. Pelagia cyanella (after AGASSIZ). 



chambers with thin roofs, into the cavity of which the repro- 

 ductive organs bulge out. 



In many forms the margins of the mouth are prolonged 

 into long fringed lobes, and in one family, the fihizostomidce 

 (e.g. Stomolophus), the margins of these lobes may fuse to- 

 gether, leaving, however, a large number of minute openings 

 along the line of fusion. These lead into canals traversing 



