Report on the Hydroids. 387 



The branches of the large, densely branched colonies are often con- 

 nected by means of "tendrils" (see p. 357 and PI. XX, figs. 5 — 7). 



Gonosomes of frequent occurrence. 



Hab.: St. 71 a, 95 a. 



Depth: 30— ca. 100 m. 



Geographical distribution: Arctic: circumpolar. — Atlantic 

 coasts of Europe and North America, California, Japan. — Subant- 

 arctic: Burdwood Bank. 



Sertularella gigantea Mereschkowsky. 

 Plate XXV, fig. 1. 



S. polyzonias var. gigantea Hincks 1874 [29] p. 151. PI. VII, 



figs. 11, 12. 

 „ gigantea Mereschk. 1878 [44] „ 330. PI. XIV, 



figs. 6, 7. 

 „ quadricornuta Hincks 1880 [30] ,, 277. PI. XV, 



figs. 1, 1 a. 

 ,. gigantea Thompson 1884 [56] ,. 5. PI. I, 



figs. 4, 5, 6, 8. 

 1887 [57] p. 393. 

 „ „ Hartlaub 1901 [24] ,, 90. Text- 



fig. 56. 

 Schydlowsky 1901 [52] p. 197. Tab. I, 

 fig. 2. Tab. Ill, fig. 31. 

 „ „ Nutting 1904 [46] p. 87. PI. XIX, 



„ ,. Jäderholm 



,. polyzonias, forma gigantea Broch 



A few sterile colonies up to ca. 4 cm. high. 



Most authors figure this species with smooth hydrothecae and 

 sa}'' nothing about ringed furrows on them. In Mereschkowsky's 

 original description (44) however, it is stated: "frequently we observe 

 three or four undulations (ribs) crossing the hydrothecae". In the 

 Danmark Expedition's specimens all the hydrothecae to hand are 

 provided with 5 — 8 (most frequently 6) close, not deep but distinct, 

 ringed furrows, which run right round the calycle, though thej^ are 

 most distinct on the external side. As division by rings is a character 

 which varies greatly in all hydroids, and as in all other respects 

 my specimens agree with the descriptions of Sertularella gigantea 

 Mereschkowsky, I do not hesitate to refer them to this species. 



Gonothecae are not present. 



XLV. 28 



