HYDROIDA II 



41 



adthecal lingueform protuberance which is lacking in Halecium Beanii. The extreme variants in the 

 other direction, {b and c; h) are markedly suggestive of broadly built gonothecce in Halecium haleci- 

 num, so that fertile colonies likewise may here often be confused. The illustration c shows a gono- 

 theca which has arisen as a heteromorphotic renovate. 



Fig. XIV a — //. Halecium scutum. 

 a. Internodium and secondary hydrotheca. Davis Strait 



100 fathoms (X 60). 



b—e. Gonothecse from a colony (9) in Kara sea (X 30). 



f—h. Gonothecae from a colony (9) in Davis Strait 



depth 100 fathoms (X 3°). 



Every gonotheca contains fully developed 



planula larvae. 



The material includes several specim- 

 ens of Halecium scutum which had previ- 

 ously been determined as Halecium Beanii; 

 this shows, that extreme caution should be 

 observed in dealing with records in literature 

 of the last-named species, the occurrence of 

 which under arctic conditions is, as above s 



mentioned, doubtful. Halecium scutum, on the other hand, is an arctic character form, with circuin- 

 polar distribution. In the waters investigated (fig. XV) it is found in the lower part of the littoral 

 region, but quite exceptionally, as at the Faroe Islands, does it penetrate to any considerable extent 

 into the warmer boreal waters. 



Halecium curvicaule v. Lorenz. 

 1886 Halecium curvicaule, v. Loreuz, Polypomedusen von Jan Mayen, p. 25, pi. 2, figs. 1 — 2. 



Colonies creeping or upright, with irregular, more rarely almost dichotomic ramification, mono- 

 siphonic hydrocaulus. Hydrothecse terminal: the next hydrotheca stalk or branch internodium proceeds 



The Ingolf-Expedition. V. 7. 6 



