The appendages of the body are reduced to branchiae, present in certain forms. A clitellum is present.
The various types of appendages described in the foregoing may be arranged in groups termed cormidia.
Thus from the original planula three appendages are, as it were, budded off, while the planula itself mostly gives rise to coenosarc, just as in some hydroids the planula is converted chiefly into hydrorhiza.
In the first place the cormus has been regarded as a single individual and its appendages as organs.
The Siphonula produced buds on the manubrium, as many Anthomedusae are known to do, and these by reduction or dislocation of parts gave rise to the various appendages of the colony.