i88 7 .] 
The Norw. North- Atlantic Exped. 
21 
and the body-cavity. Probably, even in the group of the Actinidæ, 
it may be possible to show a different development of gullet-tube, 
and in connection with it a more or less distinct separation of the 
so-called gastrovascular cavity; leading the relation in the genera 
Ægir and Fenja to be regarded as the final stage of a process of 
development already begun in other Actinidae. Butcertain knowledge 
in respect of those relations will scarcely be obtained, except by a 
logical septem of investigation of embryons; as then it will be seen 
whether they develope themselves as genuine Coelenterata, or whether 
they possibly show themselves to belong to either Pseudocoelia or 
Enterocoelia. In the meantime I am satisfied with an assignment 
of them to the great division of Actinida, but have, however, 
found it necessary to form a new family (tribus) for them. 
