- This family contains the single Australian species Clathrozoon wilsoni Spencer, in which a massive hydrorhiza Stage 4, seen in Plumularidae.
This is in some degree parallel to the cases described above, in which a planula gives rise to the hydrorhiza, and buds a polyp laterally.
The planula may fix itself (I) by one end, and then becomes the hydrocaulus and hydranth, while the hydrorhiza grows out from the base; or (2) partly by one side and then gives rise to Modified from a plate by L.
The hydrorhiza as well as to the other Agassiz, Contributions to Nat.
In some hydroids the founder-polyp, developed from a planula after fixation, throws out numerous outgrowths from the base to form the hydrorhiza; these outgrowths may be radially arranged so as to form by contact or coalescence a flat plate.