3878 REPORT—1863. 
A very remarkable feature, which one is at first sight tempted to place in 
the same category with the formation of meconidia, but which is in reality 
of an entirely different significance, is presented by Haleciwm halecinum. In 
this hydroid there is borne upon the summit of the female gonangium, in a 
situation precisely similar to that of the meconidia of Laomedea Lovéni, a 
pair of polype-like bodies. These bodies present no appreciable difference 
by which they may be distinguished from the ordinary polypites of the 
trophosome. They are of an elongated oval form, with the mouth situated 
on the summit of a short conical proboscis, which is surrounded by a circle 
of about twenty-one filiform tentacula. They are always two in number, and 
diverge from a common point of attachment, while their wide gastric cavities, 
after contracting below, communicate here with one another and with the 
tubular cavity of the blastostyle. 
I have never been able to discover any direct relation between these gonan- 
gial polypites and the generative functions of the hydroid. The blastostyle 
gives origin in the usual way, within the cavity of the gonangium, to a 
gonophore, which, so far as I have observed, is always single. This gono- 
phore never becomes extracapsular; and the ova, after being discharged 
from it by the rupture of its walls, finally escape through the summit of the 
gonangium, probably after the disappearance of the gonangial polypites. 
I may here mention a very singular body, whose exact significance I 
have never been able satisfactorily to determine, and which may be seen in 
the female gonangium of Antennularia antennina, where it is of frequent 
occurrence. It is always found floating free in the cavity of the gonangium, 
along with the ova which have escaped from the ruptured gonophores, and 
resembles an imperfectly developed medusa, with a large and apparently 
imperforate manubrium, but with its umbrella closed, and without any trace 
of gastrovascular canals. The walls of the umbrella are separated from the 
central manubrium by a considerable space, which is filled with a clear fluid. 
It may be compared toa free sporosac ; but it is much smaller than the ordi- 
nary sporosacs of the Antennularia; and I have never observed in it any trace 
of generative elements. It is probably produced, like the true gonophores, as 
a bud from the blastostyle; but I can offer no decided opinion either as to its 
origin or its ultimate destination. Its whole structure precludes the idea of 
its being an accidental parasite. 
In almost every case the gonangium, when present in the Hydroida, is 
destitute of any further covering. In certain species, however, belonging to 
the genus Plumularia and its allies, the gonangia are developed in groups, 
and each group is contained in a common receptacle, which confers upon the 
hydroid in which it exists a very striking and characteristic feature. This 
receptacle must be carefully distinguished from a proper gonangium, with 
which indeed it has been confounded in the various descriptive works on the 
Hyproma. It will therefore be very convenient to give it a special name, 
and i have already proposed for it the term corbula*, suggested by its basket- 
like form. 
I have carefully studied the nature of the corbule in Aglaophenia pluma 
(fig. 13) (the Plumularia cristata of most authors), where they may be plainly 
seen to be metamorphosed ramuli. The peculiar metamorphosis of a ramulus, 
which results in the formation of a corbula, consists in the suppression of the 
hydrothece, accompanied by the development on each side of the ramulus of 
numerous oval, hollow, alternately placed leaflets; each leaflet consisting of 
a diverticulum from the ccenosare of the ramulus, invested with a continua- 
tion of the general periderm. 
* Corbula, a basket. Proc. Roy. Soc. Edin. 1858. 
