HYDROIDS OF EASTERN CANADA 



159 



Ohelia articulata (A. Agassiz). 



Trophosome. Colony much branched, 7 cm. high; 

 stem usually simple but in some cases slightly fas- 

 cicled; main stem continuous throughout and dis- 

 tinctly stouter than any of the branches ; stem and 

 branches annulated above the origin of branches and 

 pedicels; hydrotheca deeper than wide; margin with 

 12-14 low, rounded teeth, pedicel annulated throughout 



Gonosome. Gonangium axillary, long, usually 

 longer than the stem internode, a distinct collar pre- 

 sent; pedicel annulated. 



No. 45. 

 ObcJia articulala. 



Ohelia cominissurali.s .McCrady. 



Trophosome. Colony large, 20 cm. ; main stem 

 geniculate ; branches numerous ; ste;m and branches 

 annulated above the origin of the branches and pedi- 

 cels; hydrotheca small, deeper than wide; margin 

 entire; pedicels usually annulated throughout. 



Gonosome. Gonangium axillary, obovate, smooth, 

 with a distinct collar. 



No. 46. 

 Obelia commissuralis. 



Ohelia dichoioma (Linnams). 



Trophosome. Stem 25 mm. high, slender, erect, 

 unbranched or slightly and irregularly branched ; stem 

 annulated above the nodes ; hydrotheca funnel-shaped 

 with polyhedral margin; pedicel usually annulated 

 throughout. 



Gonosome. Gonangium axillary, obovate, smooth, 

 with tapering collar; pedicel short, annulated. 



No. 47. 

 Obelia dichotoma. 



Ohelia ftahellata (Hincks). 



Trophosome. Colony 25cm. high; stem and pri- 

 mary branches branched, spreading; stem and branches 

 annulated above the origin of the branches and pedi- 

 cels; hydi'Otheca as wide as deep; margin entire, pedicel 

 annulated. 



Gonosome. Gonangium axillary, obovate, with a 

 terminal collar; pedicel short, annulated. 



No. 48. 

 Obelia flabellata. 



