30 
THE VOYAGE OF H.M.S. CHALLENGER. 
the cylindrical form of its hydrothecse. Our knowledge of the group, however, is still 
imperfect, for not only are we entirely ignorant of the gonosome, but even the true form 
of the hydranth is imperfectly known to us. It is probable, however, that this, like the 
hydranth of Lafoea and the allied genera, is provided with a conical hypostome, instead 
of having the hypostome, as in Campanularia and its allies, trumpet- shaped. 
The Challenger collection contains one beautiful representative of the genus Hebella. 
Hebella striata, n. sp. (PL XV. figs. 3, 3a). 
Trophosome. — Hydrocaulus a creeping monosiphonic stolon giving off the hydro- 
thecse from distance to distance along its length. Hydrothecse large, cylindrical, marked 
by very delicate, closely set, annular striae, contracted below into a peduncle of variable 
length. 
Gonosome not known. 
Locality. — Station 312, Port Famine, Magellan Strait; lat. 53° 38' S., long. 70° 56' 
W. ; depth, 10 to 15 fathoms. 
Hebella striata is a beautiful little Hy droid. Its relatively large hydrothecse are 
borne at intervals along a creeping stolon. They are cylindrical through nearly their 
entire height, and then gradually taper into a peduncle which varies much in length. 
They are deep and relatively wide, and with the margin for the most part very slightly 
everted. Occasionally they present a decided curvature of the axis. Their walls are 
perfectly transparent, and marked by an exceedingly delicate sculpture of fine, closely set, 
annular strise, rendering them, when viewed with a good illumination under a moderate 
power of the microscope, objects of extreme beauty. Though the hydranth was fairly 
well preserved in the specimen the form of the hypostome could not be determined. 
The specimens occur creeping over the fascicled stems of Lafoea fruticosa. 
Halisiphonia, n. gen. 
Name from aA.s, sea, and o-t<f><o v, a tube, in allusion to the tubular form of the hydrothecse. 
Generic Character. Trophosome. — Hydrocaulus a monosiphonic stolon. Hydro- 
thecse tubiform, with entire margin, destitute of operculum, with the cavity directly 
continuous with that of the peduncle or stolon, and with the hydrothecal walls never 
adnate to the hydrocaulus. Hydranth with conical hypostome. 
Gonosome. — Gonangial capsules borne by the hydrocaulus. 
The genus Halisiphonia is constituted for certain Campanularian Hydroids which 
would find their place in Lafoea as defined by Mr. Hincks. Since the publication, however, 
of Mr. Hincks’s classical work on the British Hydroid Zoophytes, our knowledge of the 
species which he would bring together under that genus has been increased to such an 
