The conception of the Dipleurula derives its chief weight from the fact that it is comparable to the early larval forms of other primitive coelomate animals, such as Balanoglossus, Phoronis, Chaetognatha, Brachiopoda and Bryozoa.
Thus Microhydra lives amongst Bryozoa, and appears to utilize the currents produced by these animals.
Subsequently 6 they were termed Bryozoa by Ehrenberg (1831).
The Bryozoa were also abundantinsomeregions (Polypora, Fenestella), including the remarkable form known as Archimedes.
At one time they were referred by some to the Polyzoa (Bryozoa), and later, by almost general consent, to the Hydroida (Calyptoblastea) among the Hydrozoa (Hydromedusae).