HYDRO1DA II 



Iceland: Adalvig (depth not stated). 

 Kara Sea: "Dijmphna". 



Sertularia mirabilis is a circumpolar arctic species, belonging to the upper and middle parts 

 of the littoral region. This being the case, it is remarkable to find it, west of the Faroe Islands, in 

 the abyssal region, as taken by the "Thor" (fig. LXXII). Within the waters investigated, Sertularia 

 mirabilis is a species of rare occurrence, otherwise found once at the north-west point of Iceland, and 

 high up in Davis Strait off the west coast of Greenland. 



2000 m. 



Fig. LXXII. Finds of Sertularia mirabilis in the Northern Atlantic. 



Gen. Hydrallmania (Hincks). 



Upright colonies with bilateral sessile to slightly imbedded hydrothecse. The hydrotheca aper- 

 ture is furnished with two lateral teeth, between which there is a smaller abcauline and a larger ad- 

 cauline sinus; median teeth lacking. In each of the two sinuses there is fastened a membrane, so 

 that the closing apparatus consists of two membranes, the adcauline with a free distal part. The polyp 

 has a well developed abcauline blind sack. 



The diagnosis as given coincides with Levinsen's definition (1913 p. 305); we have here 

 merely added the structure of the pol^p body. Levinsen points out that it may be considered 

 doubtful whether a separation between Hydrallmania and Sertularia really is altogether justified, and 

 the observations noted in the following may to a certain degree serve to accentuate the dubiousness 



