HYDROIDA II 



The gonothecse proceed from close beneath the base of the hydrothecae. They are flattened 

 pear-shaped, with a broad opening on a distally central, trumpet-shaped neck. 



Material : 



"Ingolf" St. 10 6424' N., 28 5 o' W., depth' 788 fathoms, 3,5. 



In point of habitus, this little colony much resembles Dynamena pumila. Unfortunately, the 

 state of preservation did not permit any further study of the polyps, and it is not impossible that the 

 species may be found to lack the blind sack, in which case, of course, it must be referred to the genus 

 Dynamena. There is no pronounced main stem, and the colony itself rather presents the impression 

 of being only a branch. In all other features however (fig. LXXI) it entirely agrees with earlier de- 

 scriptions, as also with colonies from West Africa, so that its specific identity is beyond doubt 



Levinsen (1913 p. 298) notes that the median tooth in this species is of the same length as 

 the lateral ones; this I have not found to be the case in any of the specimens I have been able to 

 examine. The median tooth varies somewhat, and Levinsen's statement seems to suggest that his 

 material consisted of extreme variants. 



The finding of this species in deep water so far to the north is highly interesting. In the 

 Atlantic, it was formerly only known from West Africa, and from the tropic-subtropical littoral region 

 of America to the region of Florida. It will probably also prove to inhabit other localities in the deep 

 warm atlantic waters, when sufficient investigations have been made. 



Sertularia mirabilis (Verrill) Levinsen. 



1873 Diphasia mirabilis, Verrill, Brief contributions to Zoology, p. 9. 

 1893 Sertularia mirabilis, Levinsen, Meduser, Ctenophorer og Hydroider, p. 49. 



Upright, robust, pinnate, colonies. The main stem slightly zigzag, monosiphonic, and with two 

 single rows of alternately set hydrothecse. Between two successive branches on the same side of the 

 stem there are three hydrothecse, the lowest in the angle of the branch. The branches have six, more 

 rarely only four longitudinal rows of hydrothecse, the arrangement being produced as follows: three 

 (or two) hydrothecae are set in a wreath at the same height, and the next circle has its hydrothecae 

 facing the intervals of the first. The hydrothecse are fairly deeply imbedded in the stem and branches, 

 with a free part of the adcauline wall only about half the length of the hydrotheca, or between two 

 and three diameters of the opening. The opening margin has two lateral, strongly prominent teeth 

 and an almost rudimentary median tooth in the adcauline sinus. The abcauline closing membrane 



has a free distal part 



The gonotheca: proceed from close under the base of the hydrothecse on the one side of the 

 branches. They are pear-shaped to oval, smooth, with a rudimentary neck and broad round aperture. 



Material: 



"Thor" 6io7' N., 93O' W., depth 835 metres 

 Greenland: Kudlisat, Disco (depth not stated) 



Store Hellefiskebanke, depth 2432 fathoms. 



