CNIDARIA— GENERAL 



79 



terata, there is a complicated sensory organ, the sensory body, which, 

 according to its structure, is best described as an auditory organ, but 

 perhaps serves for regulating the position of the body in the water. 



From near the aboral to near the oral pole, there run along the 

 surface of the body in S meridians 8 rows of swimming plates, the so- 



FiG. 6S. — Hormipliora plumosa, alter Chun. A aud B, From the side ; A, seen in the direction 

 c-d in Fig. C ; B, seen in the direction e-f in Fig. C. C, As viewed from the aboral or sensory 

 pole. fi-&, Chief axis ; c-d, direction of the median plane ; c-J] direction of the lateral plane ; a, 

 oral ; &, aboral pole ; m, stomach ; s, oesophagus ; sg, cesophageal vessels ; tg, tentacular vessels ; 

 ag, aboral vessel ; r, ribs ; (s, tentacle sheath ; pij, polar plates. I), Portion of a transverse 

 section through the cesophagus (5) ; ib, tentacle base ; su\ oesophageal papillEe ; ^a, branches of 

 the tentacular vessel. 



called ribs (r). If we use the terms applied to the Medusa, these ribs 

 are adradial. 



Between cesophagus and stomach on the one side and the outer 

 integument on the other, there is a jelly which is strongly developed 

 in most Ctenophora, and in which various tissue elements are imbedded. 



Gastro-canals, lined with endoderm, similar to the radial canals of 



