MUSEUM OF COMPARATIVE ZOOLOGY. 243 
cations passes around the bell parallel with the margin, and joins a 
corresponding bifurcation from the undivided tube of the hemisphere op- 
posite that in which the bifurcation first described takes place. Before 
these bifurcations join, however, each sends a loop downward, which 
approaches the neighborhood of the bell margin, but eventually returns 
to the bifurcation. 
The single ovum lies in a thin-walled sac,* which hangs from a point 
directly under the apex, and when ripe fills the whole bell cavity, some- 
times projecting a little through the opening. The free gonopbore is 
propelled in the water by violent contractions of the walls of the bell. 
The male gonophore, like the female, is often found free in the water 
in which the Agalma is confined. When attached to the stem it is 
found in clusters at or near the base of a taster midway between two 
adjacent polypites. In many live specimens of Agalma some of the 
attached male gonophores will be found to have milk-white contents. 
Like the female, the male gonophore is commonly transparent. 
The bell of the male gonophore is more elongated and larger than the 
female. It measures 2.5mm. in length and .4mm. in greatest diame- 
ter. At the apex of the bell there is a short peduncle by which it is 
attached to the adult. Through this peduncle there extends a tube, — 
the peduncular tube. There are are four thread-like simple radial 
tubes which have a direct course in the bell walls and unite with a 
circular marginal vessel. Each male gonophore has a narrow, thin ve- 
lum. The bell walls are capable of quick contractions when free from 
the axis. 
* Whether the egg in the gonophore is surrounded by a membrane by which it is 
held there, or not, no one has clearly proved. I think such is the case. In the first 
place, the homology of the gonophore with the gonophores of other genera which 
have an ovisac would seem to point to such a condition in Agalma. In my figure of 
the egg just escaping from the gonophore a structure was observed in the bell cavity 
which called to mind the ruptured walls of such a sac. After the ovum was cast, 
there is reason to suppose that the ‘‘ sac” is retained in the gonophore. Metschnikoff 
speaks of the egg of Agalma as ‘‘membranlos.” Haeckel says the egg-cell of Crys- 
tullodes, *‘ wie bei den iibrigen Siphonophoren ist ganz nackt,” and that of Physo- 
phora, ‘* wie die Eier aller iibrigen Siphonophoren sind dieselben durchaus hiillenlos.” 
** Hippopodius gleba,” writes Metschnikoff (op. cit., p. 46), ‘‘ist die einzige mir be- 
kannte Siphonophore, deren Eier mit einer freilich dusserst diinnen Membran iiber- 
zogen sind.” Hippopodius and Vogtia, according to Kolliker, have ovisacs in which, 
when in the gonophore, nwmerous ova are contained. I have also observed in a 
Eudoxia which resembles Z. Lessonii, that here also we have nwmerous ova in an 
ovisac in the female gonophore, and there are many other similar observations on 
record. 
