Gatty Marine Laboratory, St. Andrews. Lose 
long vase with a tapering process on the lip, or the filament 
had a blunt clavate tip or a cone at the end. Im another 
instance (197 metres) in which no operculum was present 
the tips of the two dorsal filaments were simply flattened and 
wider than the rest. Accompanying the foregoing were 
several—it may be young forms—in which the tips of the 
filaments were short and little tapered. The presence or 
absence of opercula, indeed, would appear to depend on no 
reliable data. 
Variability is not confined to the tips of the branchial 
filaments, for the pinne are short as in the young budding 
forms from Plymouth, or of great preportional length as im 
c rtain forms from the North Sea, the branchial fans of 
which, moreover, are about half the length of the body. The 
pinne of these are much longer and more slender than in 
any from Plymouth, though the age of the specimen has 
considerable influence in this respect. 
The number of the bristle-tufts in the anterior region ts 
likewise variable—ranging from five to ten, though a cou— 
siderable majority show seven, the number most frequent 
in the north. 
The first pair of bristle-tufts, the collar-bristles, diverges 
from the others in size, direction, and structure, and in 
these respects is closely allied to the condition in Spirorbis. 
Those from Plymouth may be taken as the type, the first 
pair of bristle-tufts being conspicuous organs directed 
forward, upward, and outward. The shaft of each bristie is 
nearly cylindrical, diminishing a little when viewed from 
behind toward the commencement of the wing, and the 
tapeiing axis can be followed as distinct from the wing to 
the hair-like tip. The broad basal part of the wing has. 
numerous (about a dozen) serrations, sloping from the base to 
the distal end in lateral view, then a hiatus occurs, followed 
by a minutely serrated tapering wing or blade. Certain 
views point to the double nature of the basal expansion of 
the wing. In some from St. Andrews several of the bristles. 
of this tuft do not show the gap separating the more boldly 
serrated base from the minutely serrated terminal region of 
the wing. Moreover, a few simple tapering bristles without 
an evident wing were prescnt. How far these may consist 
of developing forms has yet to be ascertained, but such is 
unlikely. These bristles are freely moved forward, outward,. 
and inward for various purposes, and when feeble or dying 
they stand stiffly forward and outward. In the buds these 
bristles show the same structure, and slight hollows at the 
site of the gap between the basal and distal parts of the wing 
indicate the notch, 
