. Contributions to Canadian biology. Marine biology; Natural history. HTDROIDS OF EASTERN CANADA 177 Family PLUMULARID^. Trophosome. Hydrothecae growing only on one side of the branches (hydro- cladia), sessile, more or less adnate; nematophores always present. \Gonosome. Gonophores producing fixed sporosacs, which are often protected by special modifications of the branches. KEY TO GENERA. A. Statoplean forms, , those with fixed nematophores that are usually mono- thalamic. a Gonangia protected by branchlets, each of which is an appendage of a hydro- cladium (phylactogonium). b Cauline ne
. Contributions to Canadian biology. Marine biology; Natural history. HTDROIDS OF EASTERN CANADA 177 Family PLUMULARID^. Trophosome. Hydrothecae growing only on one side of the branches (hydro- cladia), sessile, more or less adnate; nematophores always present. \Gonosome. Gonophores producing fixed sporosacs, which are often protected by special modifications of the branches. KEY TO GENERA. A. Statoplean forms, , those with fixed nematophores that are usually mono- thalamic. a Gonangia protected by branchlets, each of which is an appendage of a hydro- cladium (phylactogonium). b Cauline nematophores not crenulated, phylactogonia not jointed. Cladocarpus. hb Cauline nematophores crenulated, phylactogonia jointed. Aglaophenopsis. aa Gonangia protected by corbulae, each of which is a modified hydrocladium. A hydrotheca at the base of each gonangial leaf. Thexocarpus. B. Eleutheroplean forms, , those with movable nematoiihores that are usually bithalamic. c Gonangia not specially protected. d Hydrocladia pinnately arranged. Pliunidaria. dd Hydrocladia in whorls or scattered over the stem. Antennularia. .cc Gonangia protected 'by phylactogonia, hydrocladia branched. Schizotricha. Genus Aglaophenopsis. Trophosome. "Stem usually fascicled; hydrocladia with numerous internal septal ridges; hydrocladium margin toothed; nematophores with crenulated margin " (Nutting). Gonosome. " Gonangia protected by special appendages, growing from the proximal joint of the hydrocladia and apparently of the nature of greatly modified mesial nematophores of the proximal hydrothecae " (Nutting). Aglaophenopsis comuta (Verrill). Trophosome. Colony branched repeatedly, each branch and hydrocladium at right angles to that from which it springs; stem fascicled; hydrocladia growing on an anterior tube; internodes with about six strong septal ridges and an external longitudinal ridge; hydro- thecae obconical, with a large anterior wing-like keel; margin with five small t
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