196 THE ROYAL SOCIETY OF CANADA 



Thuiaria alba Fraser 

 PI. XXXII, Fig. 120 



Thuiaria alba Fraser, West Coast Hydroids, 1911, p. 74. 



Trophosome. — Stem stout, rigid, with several annulations near 

 the base; nodes irregular but distinct; branching regularly pinnate 

 and alternate; the branches are not nearly so stout as the main stem, 

 they are silvery white, while the main stem is much darker, a light 

 horn color; the hydrothecae are closely crowded, especially on the 

 branches, so much so that in many instances the upper point where 

 the hydrotheca leaves the branch is level with the base of the next 

 hydrotheca in order; those on the two sides alternate regularly, 

 they are tubular, curved so that the margin is nearly vertical, almost 

 wholly immersed; operculum of one abcauline flap. 



Gonosome. — (not previously described) Gonangia in two crowded 

 rows on the front of the branches, oval or oblong, with a very short 

 collar; no spines present; there are small annulations in the form of 

 fine lines running transversely. 



Distribution. — San Juan Archipelago (Fraser); Alert Bay, 

 Friday Harbor, off O'Neale I., San Juan Channel, Upright Channel, 

 oft Brown I., Port Townsend, Griffin Bay. 



Thuiaria argentea (Linnaeus) 



PI. XXXII, Fig. 121 



Sertularia argentea Linnaeus, Syst. Nat., 1758, p. 809. 

 Thuiaria argentea Fraser, West Coast Hydroids, 1911, p. 75. 



Trophosome — Colonies often growing in clusters, stems slender; 

 branches arise from all sides of the stem but are somewhat scattered, 

 these branch dichotomously but regularly to produce a graceful 

 colony; the silvery appearance adds to the effect; nodes distant; 

 hydrothecae generally alternate but occasionally nearly opposite, 

 rather distant, curved gradually outward, usually about one-third 

 free; margin with two teeth one often longer than the other; oper- 

 culum of two flaps. 



Gonosome. — Gonangia borne on the branches at the base of the 

 hydrothecae, tapering gradually from distal end to proximal, usually 

 with two marked spines; collar short; opening rather large. 



Distribution. — San Juan Archipelago, Queen Charlotte Is. (Fraser) ; 

 Rose Spit, China Hat, north of Gabriola I., Northumberland Channel, 

 Gabriola Reefs, off Matia I., off Waldron I., off Shaw I., Friday 

 Harbor, Pacific Beach. 



