142 



HYDROIDA II 



Thujaria laxa Allman. 



1874 Thujaria laxa, Allman, Report on the Hydroida "Porcupine", p. 472, pi. 45, fig. i. 



1895 Thiijaria lonchitis, Marktanner-Turneretscher, Hydroiden von Ost Spitzbergen, p. 422. 



1903 Thujaria Hjorti, Broch, Die von dem Norwegischen Fischereidampfer "Michael Sars" ge- 



sammelten Hydroiden, p. 7, Taf. Ill, figs, n 14. 



1904 Thujaria immersa, Nutting, Sertularidae, p. 66, pi. 9, figs. 3 4. 



The upright colonies are as a rule pinnate in their lower parts, spirally curved in the upper, 

 and with slender, secondarily dichotomously ramified branches, forming an open double spiral around 

 the distinct main stem, which is somewhat darker in colour. In the pinnate portion, the broad plane 

 of the branches is vertical, in the spiral it is horizontal. The stem has two opposite rows of hydro- 

 thecse; there are as a rule 4 or 5 hydrothecse between two successive branches on the same side (or 

 in the same spiral), the lowest at the corner of the branch. The branches form almost a right angle 

 with the stem, and are very nearly straight; they are irregularly segmented with a large number of 

 hydrothecae on each internodium. The hydrothecse are set subalternately in two rows on the bran- 

 ches; their symmetrical plane coincides with the broad plane of the branch. The hydrothecse are en- 

 tirely imbedded, or have a very small free distal part of the adcauline wall, never more than half the 

 opening diameter. The interval between two successive hydrothecse in the same row is as a rule 

 about equal to or slightly more than the opening diameter. The hydrotheca opening is round, the 

 margin without any indication of teeth or sinus, and has a round opercular plate abcaulinally attached. 



The gonothecse are situated on the upper side of the branches close under the basis of the 

 hydrothecae. They are oblong, narrow pear-shaped, the male distally cut off transversely, the female 

 more rounded, without neck. 



Material : 



"Ingolf" St. 3 6335' N., io24' W., depth 272 fatHoms 0,5 



- 15 66i8' N, 25059' W., 330 * 0,75 

 32 66 35 ' N, 5 6 3 8' W, - 318 3,9 

 34 6 5 i 7 ' N, 54 i7' W., 55 



44 6i 42 ' N, 9 3 6' W, 545 4,8 



51 64! 5' N, i 4 22' W, 68 7,32 



- 87 6 5 o 2 ,3'N., 2 3 5 6,2'W, no 



94 6 4 5 6' N., 3 6i 9 ' W, 204 4,1 



- 98 6 5 3 8' N, 26=27' W., 138 5,9 

 Greenland: Turner Sound, 120 



Cape Tobin, 57 (East Greenland Expedition) 



Off Henry Land, 20 



Off Henry Laud, - 160 200 



Between the Faroe and the Sh&tland Islands, depth 255 fathoms. 

 Kara Sea, "Dijmphna" [labelled Thujaria lonchitis and Thujaria articulata\. 



Thujaria laxa belongs to the lower parts of the littoral region, and the upper part of the abys- 

 sal. It is an arctic species, which has been found from Davis Strait to Tajmyr; it is also represented 



