HVDROIDA II j^^ 



The gonothecse jDroceed from close beneath the l)ase of the hydrothecce. Thev are flattened 

 pear-shaped, with a broad opening on a distalh- central, trnnipet-shaped neck. 



Material : 



"Ingolf St. 10 64°24' N., 2S°5o' W., depth 7S8 fathoms, 3,5^ 



In point of habitus, this little colony much resembles Dyi/n/iin/a pionilti. I'nforlunatel}-, the 

 state of preservation did not permit any further study of the polyps, and it is not impo.s.sible that the 

 species may be found to lack the blind sack, in which ca.se, 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 liranch. 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. 



Levins en (1913 p. 29S) 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 sjiecimens I have been able to 

 examine. The median tooth varies somewhat, and Levin sen's statement seems to suggest that liis 

 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. 



Sertularla mirabilis (Verrill) Levinsen. 

 1873 Dipliasia niirabilis^ Verrill, Hrief contributions to Zoology, p. 9. 

 1893 Sertularia iiiirabilis^ Levinsen, Meduser, Ctenophorer og Hxdroider, p. 49. 



Upright, robust, pinnate, colonies. The main stem slightl\- zigzag, monosiphonic, and with two 

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

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

 rarely only four longitudinal rows of hydrothecK, 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 hydrothecse 

 facing the intervals of the first. The hydrothecse are fairly deepl)' 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 gonothecce proceed from close under the ba.se of the hydrothecce on the one side of the 

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



Material : 



"Thor" 61^07' N., 9°30' W., depth 835 metres 

 Greenland: Kudlisat, Disco (depth not stated) 



Store Hellefiskebanke, depth 24—32 fathoms. 



