The lophophore is a simple circle in all Polyzoa except in the Phylactolaemata, where it typically has the form of a horse shoe outlined by the bases of the tentacles.
Lime is, in fact, absorbed to an enormous extent by fishes, molluscs, crustacea, calcareous algae and sponges, starfishes, sea-urchins and feather stars, many polyzoa and a multitude of protozoa (mainly the foraminifera).
References to important works on the species of marine Polyzoa by Busk, Hincks, Jullien, Levinsen, MacGillivray, Nordgaard, Norman, Waters and others are given in the Memoir (22) by Nickles and Bassler.
The most singular of the external appendages found in the Polyzoa are the avicularia and vibracula of the Cheilostomata.
The Polyzoa or Bryozoa, which has been both added to and again removed from the Mollusca between Cuvier's date and the present day.
This appears to indicate B that the Polyzoa are remotely allied to other phyla in which this type of larva prevails, and in particular to the Mollusca and Chaetopoda, as well as to the Rotifera, which are regarded as persistent Trochospheres.
With these exceptions, the existing Polyzoa are marine forms, occurring from between tide-marks to abyssal depths in the ocean.
The correctness of this association is questionable, and the Polyzoa are here treated as a primary division or phylum of the animal kingdom.
The development of Phoronis was supposed by Caldwell (2) to furnish the explanation of the relations of the surfaces in Brachiopoda, Polyzoa and perhaps the Sipunculoid Gephyrea, in which the ontogenetic evidence is less clear.
Thus we regard Rotifers as an independent stem branching off at the outset of the rise from the Platode type to higher Invertebrata The Polyzoa (q v), which in many ways recall Rotifers, appear to be equally independent.