CCELENTERATA 



81 



Anthozoa, there is also bilateral symmetry- The most striking 

 external characteristie consists of eight meridional rows of 



Fig. 68. Aurelia aurita. Development. A planula or free-swimming larva ; B,C, forma- 

 tion of mouth and oesophagus after attachment; D, transverse section of young scyphi- 

 stoma; E, scyphistoma; F, longitudinal section of same; G, strobila ; H, ephyra, lateral 

 aspect; I, ephyra, oral aspect. In A, B, C, D, F, the ectoderm is unshaded, the entoderm 

 striated, the mesogloea dotted, a, lobes of the umbrella; mnb, manubrium ; mth, mouth; 

 s.f, septal funnel ; sf. oesophagus ; /.tentacle; ///, trenioles or mesenteries. (From Korschelt 

 and Heider's Embryology.) 



vibratile plates, which are made up of fused cilia. These are 

 the organs of locomotion, and it is from them that the class 



