54 HALICORNARIA SPECIOSA. 
The two strong teeth on the front margin of the hydrotheca are so 
situated, that with the slightly everted intervening portion of the mar- 
gin they give to this part the appearance of the lip of a jug, and con- 
stitute a striking character. The pinnz arise somewhat from the anterior 
aspect of the stem, and their internodes exhibit four well-marked septal 
ridges. 
There are usually three or four male gonangia (Fig. 5) in a cluster, and 
of these one is always placed in front of the axil between the stem of 
the phylactogonium and its branch; towards the distal end of the phy- 
lactogonium the clusters are often reduced to a single gonangium. 
The branches of the female phylactogonium carry two longitudinal 
series of large cup-shaped nematophores. (Figs. 3,6.) These are situated 
exactly opposite to one another, one on the front, the other on the back 
of the branch, each series extending from the base to the apex of the 
branch, and formed by about three equally distant nematophores. Along 
the stem of the phylactogonium two series of similarly shaped nema- 
tophores also occur. These are confined to the front of the stem, and 
are disposed alternately. There is farther on the back of the phylacto- 
gonium in each axil a somewhat bracket-shaped nematophore. (Fig. 4.) 
In the male (Fig. 5) the phylactogonia as well as the gonangia are much 
smaller than in the female. Both stem and branches carry cup-shaped 
nematophores as in the female, but in the male these are all confined 
to the front. A bracket-shaped nematophore is carried on the back of 
the phylactogonium over the axil of each branch, as in the female. 
Genus HALICORNARIA Busk (modified).* 
Halicornaria speciosa. 
Py XXX YV: 
Trophosome. — Stem strong, attaining a height of about five inches, 
simple, monosiphonic pinnate almost to the base; internodes of stem 
each giving off two pinne, which are opposite, or nearly so, towards 
the base of the stem, but more alternately disposed towards the distal end, 
where the internodes become longer and more oblique. Hydrothecx wide ; 
* The genus Halicornaria founded by Busk, who used it in a wider sense, is here intended to include 
only those Plumularide which, with a trophosome formed on the general type of Aglaophenia, have gonan- 
gia which are never included in corbule or protected by phylactogonia. 
