Corystolona
Diagnostic description:
Clavid hydroids with stolonal colonies, hydrocaulus simple, unbranched, perisarc firm, terminating at hydranth base; hydranths elongate, tubular, hypostome dome-shaped, tentacles filiform, scattered over hydranth body; gonophores fixed sporosacs, arising as blind sacs beside hydranths within perisarc of hydrocaulus.