200 THE ROYAL SOCIETY OF CANADA 



Thuiaria tenera (Sars) 



PI. XXXIII, Fig. 127 



Sertularia tenera Sars, Bidrag til Kundskaben om Norges Hydroider, 



1873, p. 20. 

 Thuiaria tenera Fraser, West Coast Hydroids, 1911, p. 78. 



Trop'hosome. — Stem rather slender, branches arising from all 

 sides of the stem but somewhat scattered, these branch dichotomously 

 but regularly; hydrothecae alternate, rather distant, enlarged above the 

 base then narrowing rapidly towards the margin; fully one-half of 

 the hydrotheca is free and projects well outward but the margin is 

 directed upward; margin usually with two large blunt teeth but these 

 may be so low as not to be noticeable; operculum of two flaps or of 

 one abcauline flap. 



Gonosome. — Gonangia singly on the branches, oval, with a short, 

 stout collar and wide circular aperture; no very distinct pedicel; 

 surface free from annulations and spines. 



Distribution.— Albatross Station 2865, N. 48° 12', W. 122° 49', 

 40 fathoms (Nutting). 



As is stated in connection with T. similis, I have obtained no 

 specimens of this species from this region but as Nutting has given 

 the above mentioned locality for the species I have included it in the 

 list. The specimen described and figured is from Spitsbergen ob- 

 tained through the kindness of Dr. Marktanner-Turneretscher. 



Thuiaria thuiarioides (Clark) 



PI. XXXIV, Fig. 128 



Sertularia thuiarioides Clark, Alaskan Hydroids, 1876, p. 223. 

 Thuiaria thuiarioides Fraser, West Coast Hydroids, 1911, p. 78. 



Trophosome. — Main stem rather stout; branches from all sides 

 of the stem, placed closely enough to make a dense tuft, branches 

 branch dichotomously; hydrothecae as nearly being opposite as dis- 

 tinctly alternate, tubular below, narrowing towards the margin, a 

 small portion free; margin circular, facing upwards; operculum of 

 one adcauline flap. 



Gonosome. — Gonangia oblong or obovate, with a large circular 

 aperture; two small shoulder spines. 



Distribution. — Puget Sound (Calkins); Rose Spit, Ciayuquol 

 Sound, Swift-sure Shoal, Copal is. 



In one respect this species differs from all other known species of 

 Thuiaria, i.e. in the fact that the operculum consists of a single ad- 

 cauline (lap. On account of this difference Broch has placed it with 



