127 
size towards the point of attachment of the sporosac, and are pro- 
bably thence conveyed into the cavity of the latter, where a further 
development awaits them. 
In the condition now described, the gonophore continues during 
the early part of the season ; but at a later period there makes 
its appearance in the female gonophores a spherical acrocyst, in 
which the ova undergo further development previously to escaping 
as ciliated embryos. 
The young gonophore has the form of a compressed cone attached 
by its narrow end to the branch, and with its free end wide and 
slightly concave. In this state it is merely an offset from the 
eoenosarc of the branch, hollowed out into a cavity, which is only an 
extension of the common coenosarcal cavity, and having a delicate 
chitinous polypary moulded over its surface. 
Plumularia fcilcata, Linn. 
The gonophores in this species are of an oval form, with a tubu- 
lar apical orifice, which is closed by an opercular fleshy plug. 
They commence as a minute bud, which soon presents the form 
of a little inverted cone, having its axis traversed by a blastostyle, 
which dilates at the wide or distal extremity of the cone into a 
hollow opercular enlargement. From the blastostyle a single spo- 
rosac is produced as a lateral bud, which ultimately, by the arrest 
of that portion of the blastostyle between it and the operculum, 
acquires a terminal position, being now supported on the summit of 
a very short peduncle which springs from the base of the gonophore, 
and which is nothing more than the proximal extremity of the ori- 
ginal blastostyle. From this point the sporosac extends towards 
the summit of the gonophore, which has acquired an oval form, and 
which at last it completely fills. From the cavity of the opercular 
body which closes the summit of the gonophore several more or less 
branched coecal tubes are given off into the interior of the gonophore, 
where they may be seen running for some distance along the inner 
surface of its walls towards its attached extremity. 
The generative elements are produced, as usual, between the 
ectoderm and endoderm of the manubrium of the sporosac ; and by 
their increase of volume, and consequent pressure, occasion, at least 
in the female sporosacs, the gradual absorption of the spadix, which 
