- Diagram showing possible modifications of medusiform and hydriform persons of a colony of Siphonophora.
Hydranth (hydriform person)expanded.
Hydranth (hydriform person) contracted.
Sporosac springing from m, a modified hydriform person (blastostyle): the genitalia are seen surrounding the spadix or manubrium.
I, The horny cup or hydrotheca of the hydriform persons; 1, medusiform person springing from m, a modified hydriform person (blastostyle); n, the horny case or gonangium enclosing the blastostyle and its buds.