[fraser] HYDROIDS OF THE VANCOUVER ISLAND REGION 189 



Selaginopsis triserialis Mereschkowsky 

 PI. XXIX, Fig. 108 



Selaginopsis triserialis Mereschkowsky, Ann. and Mag. N.H., 5th. 



ser., 2 1878, p. 435. 

 Sertularia incongrua Torrey, Hyd. of the Pacific Coast, 1902, p. 69. 

 Selaginopsis triserialis Fraser, West Coast Hydroids, 1911, p. 67. 



Trophosome.— -Stem rather slender for the genus, reaching a 

 height of 30 cm., with long branches arranged alternately but not 

 regularly ; hydrothecae in two rows on the stem and sometimes also 

 on the proximal portions of the branches but in three rows in the 

 distal portions; more distant than in other species of the genus; 

 almost wholly immersed; aperture oval; operculum a single abcauline 

 flap. 



Gonosome. — "Gonangium oblong-oval in shape, with a large ter- 

 minal aperture" (Nutting). 



Distribution. — Nanoose Bay, off Waldron I. 



I have not found the gonangium. Nulling found "a single dis- 

 torted gonangium" and described it but did not figure it. 



Genus SERTULARELLA 



Trophosome.— Hydrothecae in two rows, alternate, usually with 

 3 or 4 teeth and an operculum with 3 or 4 flaps. 



Gonosome.— Gonangia usually supplied with ridges or corrugations. 



Key to the species of Sertularella found in the Vancouver I. 

 region. 



A. Hydrothecae with four teeth. 



a. Hydrothecae wholly immersed S. albida. 



b. Hydrothecae partly free. 



1 , Hydrothecae without annulations or rugosities 



S. polyzonias 



2. Hydrothecae annulated or rugose. 



i. Stem slender, hydrothecae distant S. tenella 



ii. Hydrothecae decidedly rugose 5. rugosa 



iii. Hydrothecae not large, more than half free . 5. conica 

 iv. Hydrothecae large, scarcely immersed 5. tanneri 



B. Hydrothecae with three teeth 



a. Stem erect, stout, hydrothecae usually smooth 5. turgida 



b. Stem erect, hydrothecae annulated 5- pedrensis 



c. Stem flabellate, gonangia contorted S. pinnata 



d. Stem lax, hvdrotheca? smooth S. tricuspidata 



