19, which represents the septal arrangement of Streptelasma corniculum from the lower Silurian.
I), and becomes perforated in the same way at its outer side by a "septal ostium," forming as it were the rudiment of a ring-canal.
The septal ostia become widened and the gastral cavity flattened, whereby the taeniolae become comparatively shallow columns, similar to the septal nodes or cathammata of other forms.'
(After Claus.) by Friedemann (3), a recent investigator of the subject, that the infundibular cavities appear late in the scyphistoma and have no relation either to the septal muscles or to the subgenital cavities of the adult.