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, i.e., 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, i.e., 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 teeth on each side; intrathecal 

 ridge small, oblique; supracalycine nematophores long, 

 tubular, with crenulated margin; mesial nematophore 

 neai'ly straight, spur-like, margin crenulated; three 

 cauline nematophores to each node. (From Nutting's 

 description.)- ^ 



Gonosome. " Gonangia borne on the terminal 

 branchlets, oblong-oval, with latero-terminal apertures; Apiaoj^iielwpsis comuta 



protective appendage unbranched or bifurcated, borne (after Nutting). 



at the side of the proximal hydrotheca on each hydro- 

 cladium, having a hydrotheca at its distal end, and two when it is forked; there is 

 an axial cavity divided by numerous septal ridges" (Nutting). 



T9550— 12 



