HYDROIDA II 



71 



The gonothecse are attached to the apophyse beside the sessile sareotheca. Fully grown gon- 

 angia have not yet been found. 



Material: 



"Ingolf" St. 27 64°54' N., 55°io' W., depth 393 fathoms 3,8° 



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

 Greenland: Davis Strait (without further details) [type specimens of Plumularia groenlandica\. 

 Iceland : Ingolfshofdi g 1 / 2 miles in N. by E. 1 j 2 E., depth 53 fathoms. 



L,ev ins en (1893 P- 63) gives a very detailed description of this species, which he incorrectly 

 regards as different from Sars's Plumularia grin-Mima. He has however, in common with others who 



200 m. _ _ _ _ 600m. ._ looom. 2000m. 



Fig. XXXV. The localities of Polynemertesia gracillima in the Northern Atlantic. 

 In the hatched region the occurrence according to the literature is common, although scattered. 



have investigated the species, overlooked its typical sessile sareotheca on the apophyses (fig. XXXIV) 

 It is noticeable that a mamelon occurs not only on the primary but on all the apophyses in the colony. 

 The idea that it should, as Nutting (1900) believes to be the case with other species, form the point 

 of origin of the gonothecse, is due to inadequate investigation; the gonothecse have their point of 

 attachment by the side of this sareotheca. Levinsen's description incorrectly gives the impression 

 that he has had grown gonothecse before him at the time; they are, however, only quite young stages, 

 and grown gonangia have thus not been described for this species. 



Polynemertesia gracillima is plainly a southern visitor to the northern waters, and has strangely 

 enough not yet been recorded in the British waters (fig. XXXV). The "Ingolf" was able to furnish 



