Fig, 41. — Obelia sp. A, portion of a colony, with certain parts shown in longi- 

 tudinal section; B, medusa; C, the same, with reversed umbrella; D, the same, 

 oral aspect; Ed. 1, 2, buds; bis, blastostyle ; ctr, ccenosarc ; ect, ectoderm; 

 end, endoderm ; ent, enteric cavity; gth, gonotheca (gonangium) : hth, hydro- 

 theca ; /, Hthocyst ; vi.bd, medusa-bud; mul>, manubrium; msgl, mesoglaea ; 

 mth, mouth; fi, perisarc; P, 1, 2, 3, 4, polypes; rad.c, radial canal; /, 

 tentacle; vl, velum. 



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