CHAPTER III 

 C(ELENTERATA 



This phylum, which by some authors, is made to include the porif era, 

 though important scientifically, is one of the least importance economic- 



Pic. 8. Hydrozoa. A, part of a colonial species, Obelia. i, ectoderm; 2, 

 entoderm; 3, mouth; 4, ccelenteron; 5, coenosarc; 6, perisarc; 7, hydrotheca; 8, 

 blastostyle; 9, medusa bud; 10, gonotheca. B, free-swimming medusa of Obelia. 

 i, mouth; 2, tentacles; 3, reproductive organs; 4, radial canals; 5, statocyst. C, 

 larva (planula) of Laomedea. A, Xio; B and C, more enlarged. (From Hegner, 

 College Zoology; A, after Parker and Haswell; B, after Shipley and MacBride; C, 

 after Parker from Allman.) 



ally. It includes a large number of aquatic forms, mostly marine^ 

 and mostly soft, even jelly-like, in character; they are radially sym. 



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