370 REPORT—1863. 
present the form of a simple sac only at first ; for by the time that their con- 
tents have approached maturity, new spermatogenous tissue becomes apparent 
between the endoderm and ectoderm of their supporting peduncles, and these 
two membranes thus become separated from one another so as to form a second 
sac immediately behind the first, while a third may in the same way be 
formed behind the second, the gonophore thus acquiring the peculiar monili- 
form or polythalamic conformation characteristic of this genus (fig. 7). It will 
be at once apparent that the separate chambers presented by this peculiar form 
must not be regarded as so many distinct gonophores; the whole moniliform 
series ought rather to be viewed as a simple adelocodonic gonophore, in which 
the endotheca is not uniformly separated from the spadix by the intervention 
of the spermatogenous tissue, but remains at intervals permanently adherent 
to it. Among the free meduse an entirely analogous phenomenon occurs in 
a Sarsia-like medusa of unknown trophosome, which I captured in the towing- 
net on the south-west coast of Ireland (fig. 8). In this, the manubrium, which 
is extraordinarily extensile, and can be projected for a great length beyond the 
umbrella, was enlarged at distinct intervals by the development of the gene- 
rative elements between its ectoderm and endoderm. The specimen captured 
was a male, and the manubrium, when extended, presented, by the mode in 
which the spermatogenous tissue was developed in its walls, five elongated 
cylindrical enlargements, separated from one another by long thin intervening 
portions, in which the ectoderm and endoderm of the manubrium continued 
in direct contact with one another, no generative element being there deve- 
loped. The spermatogenous mass which occupied the free end of the manu- 
brium was divided into two by a shallow strangulation. The peculiar mode in 
which the generative elements are developed in the manubrium of Dipurena, 
a nearly allied genus described by M°Crady*, would seem to afford an exam- 
ple of an analogous phenomenon. 
The gonophore may be borne upon a distinct peduncle, which may be 
simple (Syncoryne eximia, &c.) or branched (Tubularia indivisa, Corymorpha 
nutans, &c.), each branch then bearing a gonophore on its summit; or the 
peduncle may be evanescent, and the gonophore become sessile (Laomedea 
flexuosa, &e.). 
The gonophores, whether phanerocodonic or adelocodonic, may be destitute 
of any further covering, and will then, while attached to the trophosome 
(Coryne, Clava, &c.) or to the gonoblastidium (Dicoryne, Hydractinia, &e.), 
have their surface in immediate contact with the surrounding water (fig. 2 ¢). 
In other cases the gonoblastidium, with its gonophores, may be surrounded 
by a close case or capsule, formed by a layer of ectodermi with an external chiti- 
nous investment (Campanularia, Sertularia, &c.) (fig. 1f). I have elsewhere 
designated this capsule by the name of “ gonangium’’t. The gonoblastidium 
extends through the axis of the gonangium as a cylindrical column, bearing 
the gonophores as buds upon its sides, and generally expanded at its summit 
into a conical plug or disc, by which the gonangium is here closed. It 
will be convenient to distinguish specially this modification of the gono- 
blastidium; I have elsewhere used for it the term “ blastostyle”’t, and shall 
in the present Report employ the same term in the sense thus defined. 
In some cases the contents of the gonangium escape, when mature, by the 
simple rupture of the summit (Plumularia, &c.). In others, however, the 
* M°Crady, op. cit. p. 135. 
+ Tévos, and ayyetov, a vessel. “On the Structure and Terminology of the Reproduc- 
tive System in the Corynide and Sertulariade,” Ann. Nat. Hist. July 1860. 
t Bdaords, a bud, and ordXos, a column. Proc. B.S. Edin. 1858. 
