6 GEORGE BUSK. 
flattened in the spirit specimen, is, in the natural condition, 
cylindrical, and probably, when distended, sufficiently stiff 
to support the upper portion in an upright position, whose 
weight, of course, must be very littlein the water. The wall 
of the peduncle, though perhaps rather thicker than the web, 
is perfectly transparent, and, so far as I can make out, quite 
homogeneous; and in the interior, in the spirit specimen, 
nothing is to be seen except a few minute nuclei and slender 
branching threads, probably belonging to an extremely 
delicate endosarc, and which it is allowable to suppose may 
represent the so-called “colonial nervous system,” seen by 
Smitt in the radical tubes of his B. wmbella. 
The zocecia are about 0:045 inch long by 0°02 in width, 
which is tolerably uniform from top to bottom. The outer 
border, as in most species of Bugula, is hollowed on the ex- 
ternal border and towards the lower end in most of the 
zocecia, a sort of step is thrown out (Pl. I, fig. 1), upon 
which is articulated the avicularium. The inner border is 
evenly rounded, and the upper and inner angle is completely 
rounded off, whilst the external is produced and crowned 
with a short, pointed, spinous process. 
Viewed behind, the zocecium is convex and the surface 
perfectly smooth, without a vestige of any transverse ridges. 
The outline is much the same as in front, and the outer 
border is acute, the inner rounded. At bottom the zoccium 
is seen to arise from the back of the subjacent one by a con- 
stricted neck, on the outer side of which there is a chitinous, 
thickened, ring-shaped process, which appears to represent 
the spot from which, in the lower part of the branches, the 
radical tubes spring; and the insertion of the zoccium 
appears to be also surrounded with a rather thick, chitinous 
ring. The oecia are of large size, attached to the middle of 
the summit of the zocecium in front, and projecting forwards 
in the form of a wide shallow hood. 
The avicularia are about 0°02 inch long and about 0°006 
wide. The mandible is about 0°01 inch in length, and 
much curved; within it presents the usual arrangement of 
muscles, and a thickened, glandular, (?) digitiform sac or 
pouch. 
Within the zocecium a rather large polypide is lodged, of 
the usual conformation and muscular connections, and 
having about twenty-four or twenty-six tentacles. So far 
there is nothing very remarkable: but other peculiarities 
remain to be mentioned, possessed in common by this and 
the other species of Ainetoskias. These are—1l. The ex- 
istence of a distinct muscle, which, arising from the front of 
