Gatty Marine Laboratory, St. Andrews. 195 
In this the cephalic collar is well developed, forming a 
Sheath for the base of the tentacles. The filaments of the 
branchiz, which are fourteen in number, terminate distally 
in a tapering subulate process, which extends considerably 
beyond the pinnze. The nail-shaped operculum presents a 
minutely cellular or reticulated structure, when viewed by 
a high power from above, and a series of concentric rings. 
A considerable process or talon occurs beneath it, the lower 
edge of which varies in outline—sometimes being irregular, 
at other times smooth. The distal concavity frequently 
contains mud and minute alge. 
The body has the typical coil, three bristled segments 
occurring in front and twenty to thirty posteriorly. The 
most powerful muscle seems to be that on the concave side 
of the coil. The collar (first) bristles have straight shafts 
dilating into a broad web at the base of the tip, which is 
bent backward, is of moderate length, finely tapered, and 
minutely serrated. The basal web is striated, each of the 
striz ending in a sharp point, whilst the distal blade slants 
obliquely to the serrated edge. The second tuft has bristles 
with rather broad wings, and the blade tapers rather sud- 
denly to a very fine point, so as to give a character to the 
bristle. The third tuft has both winged and sickle-shaped 
bristles, the edge of the latter being serrated. 
The posterior bristles are minute, and project little 
beyond the surface. They are geniculate at the tip, being 
bent nearly at a right angle to the shaft and coarsely 
serrated. The anterior hooks are stated by Miss Pixell 
to be of ordinary shape, with about twenty teeth. The 
tube is described by Miss -Pixell as dextral, large and 
flat, thick and opaque, slightly roughened, but without 
definite growth-lines. A slight median ridge and sometimes 
one on either side; the aperture has, however, an entire 
margin and measures 2 mm. across. The Irish examples 
from Blacksod Bay, kindly forwarded by Mr. Southern, 
were in dense clusters on stones and shells, sometimes only 
the aperture being visible, whilst the tube itself formed a 
lax spiral, quite different from the original account of 
Miss Pixell, though it is still large. In lateral view the 
elongated spires of some of the masses gave an unusual 
depth to the Spirorbid coating. Some examples, indeed, 
formed an elongated spiral tube, after the manner of the 
horn of the Indian Antelope, or even that of the Koodoo. 
Originally the tube appears to be small and flat, then, as the 
annelid increases in size, the tube thickens, becomes loosely 
spiral, and keeps pace with the growth of sponges or other 
3% 
