[fkaser] HVDROIDS OF THE VANCOUVER ISLAND REGION 161 



branched, some of the branches being almost as long as the main stem; 

 stem and branches flexuous, annulated throughout; pedicels rather 

 short, annulated; hydrotheca with proximal portion oval and distal 

 portion conical, no distinct margin; segments long and slender; hy- 

 dranths long and slender with 14-15 tentacles. 



Gonosome. — Female gonangia oval, sessile or on short annulated 

 pedicels, in the axils or taking the place of hydrothecae; sporosacs 

 extruded into an acrocyst; male gonangia similar in position to the 

 female but more nearly cylindrical in shape. 



Distribution. — On Gonothyrœa clarki, found at low tide at Jesse 

 I., Departure Bay. 



Genus STEGOPOMA 



Trophosome. — Hydrotheca with an operculum formed of two 

 membranes folded lengthwise, and which come together, roof-like, 

 with their long edges; each of these is separated from the remainder 

 of the hydrotheca by a curved line; at each side the hydrothecal wall 

 forms a triangular, gable-like structure, between the two opercular 

 membranes. 



Gonosome. — Levinsen, who established this genus, gave no char- 

 acters for the gonosome and no one seems to have done so since. In 

 some cases at least, probably in all, reproduction takes place by fixed 

 sporosacs. 



Stegopoma plicatile (Sars) 



PI. XVIII, Fig. 66 



Lajœa plicatile Sars, Selsk. Forhandl., 1862, p. 31. 



Stegopoma plicatile Levinsen, Meduser, Ctenophorer og Hydroider, 



1893, p. 36. 

 Stegopoma plicatile Fraser, West Coast Hydroids, 1911, p. 45. 

 Stegopoma plicatile Broch, Coelentérés du Fond, 1912, p. 11. 



Trophosome. — Stem large, strongly fascicled, the number of tubes 

 in the fascicle being from 3 up; only the extremity of the branchlets 

 are simple; the hydrothecae are long and almost tubular, sometimes 

 straight, but more commonly curved, often with a short pedicel but 

 sometimes sessile or even in lateral contact with the branch; oper- 

 culum consisting of the regular two membranes meeting along a 

 ridge, with the walls of the hydrotheca produced to form the gable 

 and to support the operculum. Broch speaks of a creeping variety 

 as well as the erect, but I have seen no specimens of it. 



Gonosome. — I have not obtained any gonangia nor have I seen 

 any good figure of one. Sars says the gonangia are large, cylindrical, 



