PHYLUM CGELENTERATA 



133 



Order 3. Cubomedusae. — Scyphozoa with four perradial 

 tentaculocysts; tentacles interradial; umbrella four-sided, cup- 



Fig. 82. — Scyphozoa. A, Tessera princeps, order Stauromedus-e. B, Peri- 

 phylla hyacinthina, order Peromedus^;. C, Charybdea marsupialis, order Cubo- 

 medus.e. G, gonads; Gf, gastral filaments; Ov, gonads; Rf, annular groove; 

 Rk, marginal bodies; km, circular muscle; T, tentacles. (From Sedgwick, 

 after Haeckel.) 



shaped; no alternation of generations. Example: Charybdea 

 (Fig. 82, C). 



Order 4. Discomedusae. — Scyphozoa with four or more 

 perradial and four or more interradial tentaculocysts; umbrella 

 disc-shaped; alternation of generations. Examples: Amelia 

 (Fig. 79), Pelagia, Cassiopea. 



4. Class III. Anthozoa (Actinozoa) 



There are no medusae among the Anthozoa. The polyps 

 may be distinguished from those of the Hydrozoa by the pres- 

 ence of a well-developed stomodaeum or gullet, which is fastened 

 to the body-wall by a number of radially arranged membranes 

 called mesenteries. Many of the polyps are solitary, but the 

 majority produce colonies by budding. Most of the Anthozoa 



