6 
of growth is Halecium curvicaule, which has been described under 
various names according to the shape of the colony: H. curvicaule 
v. Lorenz, H. mirabile Schydlowsky, H. repens Jåderholm. The 
Greenland colonies of Halecium minutum with compound- stem must 
be regarded from the same point of view. Several rhizocauli cover 
the support (hydroid colonies, especially Halecium muricatum), sen- 
ding.out now and then small, sparingly branched stems, as is usually 
the case in this species; sometimes, however, a number of the 
rhizocauli seem to run together and leave the support as a bundle 
of tubes, a compound stem. This stem can divide into compound 
branches, consisting of several tubes, tapering in thickness (consisting 
of fewer tubes) towards the distal end. Moreover small simple 
branches issue, exactly with the shape of the small, slightly branched 
stems of a common H. minutum, bearing a number of hydrothecæ 
which do not differ in any respect from the common H. minutum. 
On the stems and branches several of the large characteristic female 
gonothecæ are present, thus no mistake as to the identification 
being possible. — Since the colonies in question are growing on hy- 
droids, most of them on H. muricatum, one could think, perhaps, 
that the compound stem mentioned was only a number of rhizo- 
cauli of the H. minutum growing on a little branch of the H. 
muricatum. Further investigations have shown, however, that this 
is not the case; all the tubes of the compound stem belong to H 
" minutum and issue from the rhizocauli running over the surface of 
the stem and branches of the muricatum-colony. 
In 1909 Broch described and figured (1909 b, p. 153, text- 
figs. 13, 14) some colonies of a small species of Halecium very 
much alike H. minutum, but the colonies were sterile, and accor- 
dingly they could not be identified with certainty. On some of the 
colonies Broch saw rows of hydrothecæ (pseudohydrocauli) very much 
like the pseudohydrocauli of the species described by Jåde rholm 
(1908) as H. telescopicum Allman; but as this species has a com- 
pound stem, Broch would not refer his colonies to the same species. 
Now we have seen that H. minutum may appear with compound 
