In Cephalodiscus the coenoecium is more massive, and may contain a continuous irregular cavity in which the zooids live (Demiothecia), or may be secreted in such a way that each zooid has its own independent tube (Idiothecia, Orthoecus).
The zooids are a modification of the type of structure known in Balanhglossus, from which they differ principally in the following respects: (i.) The alimentary canal, instead of being straight, has a U-shaped flexure, the dorsal line between the mouth and the anus being short.
The original specimen of C. dodecalophus contained exclusively female zooids, in which a single pair of ovaries (figs.
Associated with these males are neuter zooids, which usually possess no functional repro ductive organs, but have in I -...
Hence it is necessary to distin guishbetween,first,the"zooids," FIG.
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