12 SYDNEY J. HICKSON ann F. H. GRAVELY. 
The fortunate preservation of a small and probably young branching stem of 
specimen A, with gastrozooids at its proximal end similar to those of the basal parts 
and at its distal end similar to those of specimen B ; with a smooth surface similar to 
that of specimen B, and ramifying and growing without any axial support as 
specimen B does, may be regarded as conclusive evidence that the specimens belong to 
the same species. 
The species resembles //ydractinia in having sessile hydranths, a thick membranous 
hydrorhiza covered with a continuous sheath of ectoderm and provided with a lacunar 
chitinous skeleton, and in having adelocodonic gonophores. 
On the other hand, it differs from many of the species of //ydractinia in 
forming large unsupported rhizocauline branching stems, and in the absence of 
dactylozooids. 
A species that has close aftinities with H. dendritica is H. angusta, from 71° 8. and 
87° W. 400 metres (Hartlaub 9: pp. 7-8; Pl. IV., figs. 1-6). It forms branching (?) 
cylindrical rhizocauline stems. It has also tentaculate blastostyles and no dactylo- 
zooids. But it has thorny processes on the surface, which in our species are confined 
to the basal part; the gastrozooids of our species are quite twice as large and the 
tentacles are more numerous than in //ydractinia angusta. 
It differs from /Zydrodendrium gorgonoides (Nutting 20: pp. 936-938; Pl. I., 
figs. 1-6; Pl. VIL, figs. 1-2) from Hawaii, in having definite blastostyles, in the 
presence of a large hypostome on the gastrozooid, in the colonies being unisexual, 
and in other characters. It resembles Hydrodendrium in the occurrence of branching 
brittle rhizocauline stems, in the absence of spines on the surface, and in the 
absence of dactylozooids. 
Hydractinia angusta and Hydractinia dendritica form two interesting links in a 
chain connecting the ordinary species of Hydractinia with Hydrodendrium. It may be 
noted here that im addition to the species of //ydractinia mentioned above that have no 
dactylozooids, Hydvaetinia parvispina {Hartlaub), 7. earnea, var. inermis, I, humilis, 
and //. provuti (Koss.) are said to have no dactylozooids ; and in other species described 
by Bonnevie (6), Hincks (11), and Allman (2) no mention is made of these peculiar 
zooids. The presence of dactylozooids cannot therefore be regarded as a character of 
the genus. 
FAMILY TUBULARIIDAE. 
GENUS TUBULARIA (Linn. emend. Allman). 
We have found in the collection what appear to be three distinct species 
of Tubularia, but of these, one is represented by a single hydranth, and one 
by two hydranths. The third species agrees fairly well with the description given 
in Bale’s Australian Zoophytes of a species described’ in MS. by Halley from 
Hobson’s Bay. 
