n8 



HYDROIDA II 



The Faroe Islands: 8 — 10 miles N. of the Faroe Islands (without further details) 



6 miles N. by W. of Store Kalso, depth 60 fathoms 



7 — N. by E. of Myggenses point — 57 

 Boronses i3/ 4 miles in N. 75° \Y. 30 

 Deep hole at north point of Nolso — 100 

 13 miles W. by S. of Munken — 150 



I have in earlier works (1908, 1909) united this species with the next, the more finely built 

 form Abietinaria filicula (Ellis et Solander), having overlooked the specific character which lies in the 



2 00 rti. — ■.«■ — (00 m. ._ „ 1000 m. _. 2000m. 



Fig. LX1I. The distribution of Abietinaria abietina in the Northern Atlantic. 

 In the hatched regions a common occurrence is reported. 



peculiar diaphragm of Abietinaria abietina, as pointed out by Levinsen (1893 p. 56). Generally speak- 

 ing, the robuster stucture of the colonies will obviate an}* doubt when dealing with the last-named 

 species, but this is not always the case. Occasionally, Abietinaria abietina may assume a finer struct- 

 ure (cf. Broch 1908) and it was from observation of such doubtful colonies that I was led to combine 

 the two species under a common name. In such dwarf colonies, however, identity may easily be deter- 

 mined by examination of the diaphragm, which in Abietinaria abietina is typically bilateral, whereas 

 in Abietinaria filicula the development is almost entirely radially symmetrical. 



Abietinaria abietina is a circumpolar boreal species, capable of penetrating far into the arctic 

 area, albeit its occurrence there is more sporadic. It can also move far to the south, and is found 

 in the Mediterranean and at Madeira. It belongs really to the littoral region, but may exceptionally 



