14 SYDNEY J. HICKSON a AND F. H. GRAVELY. 
Fydrosome. 
branches ramifying in a sponge. The hydrocaulus is unbranched, and rises to a 
The hydrocaulus springs from a hydrorhiza composed of thin 
height of about 40 mm. It is of almost uniform diameter throughout. 
The perisare is thin, membranous, and ends rather abruptly a little below the 
hydranth, which is marked off from the hydrocaulus by a slight constriction. The 
height of the cylindrical hydranth is about 5 mm. There is a dense tuft of about 
60 tentacles round the mouth. The proximal circlet is composed of about 25 tentacles, 
7 mm. in length. 
Gonosome.—There are about nine bunches of closely packed spherical gonophores ~ 
attached in the usual manner to the inner or distal side of the-proximal circlet of 
tentacles. From the position they occupy in the spirit specimen lying close alongside 
the wall of the hydranth, it seems probable that in life the hydranth was pendulous. 
The blastostyles are about 5 mm. in length and the gonophores are 0°9 mm. in 
diameter. The structure of the gonophores is extremely interesting. The umbrella 
wall consists (fig. 34) of an outer layer of simple ectoderm, a thin layer of mesogloea, 
and an inner layer of ectoderm cells, which appear to be tri-radiate in section, one of 
the radii projecting into the mass of sperm cells, and the other two radii forming a 
continuous thin membrane lining the sub-umbrella cavity. At the distal extremity 
of the gonophore the inner and outer ectoderm layers are continuous, and between 
them the umbrella wall is thickened and contains a ring of endoderm cells. In some 
cases there are four short tentacular thickenings of the ectoderm at the mouth of the 
gonophore (fig. 34). In the centre of the gonophore there is a well-marked manubrium 
or spadix, with a lumen and without any clearly-defined ectoderm covering. The 
sperm cells entirely fill the space between this endodermal spadix and the umbrella. 
wall. The sperm cells lying in contact with the manubrium are evidently in the 
earlier stages of spermagenesis, those lying at the periphery of the sub-umbrella 
cavity in the later stages of spermagenesis (fig. 34, sp.), so that it may be said that 
the sperm cells ripen from within outwards. 
The absence of any well-defined canals in the gonophore, and the presence of 
four conical rudimentary tentacles, suggests aftinities with Agassiz’s sub-genus 
Thamnocnidia (1: see 2, pp. 399-400, 406, and 416), but apart from this it is not 
possible to find any close affinities with other species of the genus. 
TUBULARIA LONGSTAFFI. 
(Plate I; fig. 11.) 
Locality.—No. 6 hole, April 8th, 1903; 124 fms. 
Only a single specimen of this magnificent Tubularian zoophyte was found, and 
it bears unfortunately only a single hydranth. As it appears to be quite distinct 
from Tubularia hodgsoni and does not agree with any other species of the genus 
that has hitherto been described, we propose to call it Tubularia longstaffi. 
