6o 



HYDROIDA II 



. . _,IOOO m. 2000 m. 



Fig. XXVII. Localities of Polyplumaria frutescens in the Northern Atlantic. 

 In the hatched parts the literature notes a scattered occurence without further data. 



of the hydrotheca. The secondary hydrocladitim proceeds from beside the basal hydrotheca of the 

 primary hydrocladium, and is of the same appearance as this. 



The gonothecse are fastened to the stem or the branch apophyses by a very short stalk. They 

 are oval, with a large, somewhat asymmetrical distal opening, and with four sarcothecse at the base. 

 Material : 



"Thor" 3557' N, 53 5 ' W., depth 740 metres 



Iceland: Vestmano, 510 



According to Ritchie (1911 p. 223) the number of unpaired small distal sarcothecse on the 

 internodium should vary from one to three. No such variation could be discerned in the colonies 

 investigated by me. 



Polyplumaria flabellata is a very rare visitor in the northern waters (fig. XXVIII) and occurs 

 here only in the deeper water layers. The species has altogether its main distribution in the upper 

 parts of the abyssal region. The Vestmanna Islands mark the most northerly point where it has been 

 found up to now; in Greenland waters it would seem to be entirely lacking. 



Polyplumaria profunda (Nutting). 

 1900 Plumularia profunda, Nutting, Plumularidae, p. 66, pi. 8, figs. 2 3. 



Upright, composite pinnate colonies with branched polysiphonic main stem. The primary tube 

 which is seen in the outer parts of the colony is divided by transverse nodes into internodia, bearing 



