ABSTRACT
The Cnidaria are divided into four discrete classes; Scyphozoa, Cubozoa, Hydrozoa and Anthozoa. The evolutionary based status of each of them within the cnidarian system is viewed by different taxonomists in different ways (Hadzi 1963, Uchida 1963, Rees 1966, Werner 1973, Petersen 1979, 1990, Stepanjants 1988, Grasshoff 1991a,b, 1997). However, the discussion of this problem is beyond the scope of the present review.
