Ill] 



CTENOPHORA 



79 



The lower part of the hydroid regenerated the head, exactly as a 

 Hydra can do if the head with its ring of tentacles be cut off. 

 Later this process of renewal became hurried on until it com- 

 menced before the separation of the head was complete and thus 

 we have the Scyphistoma stage. It is a strong support of this 



, 5 



FIG. 35. Hormiphora plumosa. After Chun. Side view. 



1. Mouth leading into stomach. 2. Aboral pole with sense organ. 



3. Funnel. 4. Paragastric canal running back towards oral .pole. 



5. One of the eight bands of fused cilia. 6. One of the eight canals 

 running towards 5. 7. A tentacular pouch. 8. A tentacle. 



9. Gelatinous tissue. 



theory that the polyps of the genus Tubularia are often cast off in the 

 winter-time and are regenerated from their basal stumps in the spring. 

 A fourth great division of the Coelenterata is constituted by the 



animals called Ctenophora (Gr. KTC/S, KTCI/OS, a comb). 



These are widely different from Hydromedusae, 

 Actinozoa, and Scyphozoa. They never bud and they have no thread 



