COELENTERA TA 



75 



eight cords of fatty cells attached to the oesophagus in both 

 kinds of polyps. 



Class C. CTENOPHORA. 



Chaeacteeistics. — Pelagic Coelenterata, usually spheroidal, more 

 rarely hand-shaped in form. Eight meridional rows of 

 vibrating plates composed of fused cilia form the locomotor 

 apparatus. A large pair of retractile tentacles are usually 

 present, which can he withdrawn into pouches. At the 

 ahoral pole is a special sense organ. Tliey are all herma- 

 phrodite, and pelagic. 

 This group of animals possesses considerable importance 



from a phylogenetic point of view. Haeckel has described a 



Fig. 53. — Hormip/wra plumosa. After 

 Chun. Side view. 



1. Mouth leading into stomach. 



2. Aboral pole with sense organ. 



3. Funnel. 



4. Recurrent canals running back to- 



wards oral pole. 



5. One of the eight bands of fused cilia. 



6. One of the eight canals running to- 



wards 5. 



7. A tentacular pouch. 



8. A tentacle. 



9. Gelatinous tissue. 



remarkable Anthomedusan named Ctenaria ctenophora which 

 has many of the characteristic features of a Ctenophor ; whilst 



