182 Prof. M‘Intosh’s Notes from the 
the other side. It is usually thrown into various frills, but 
it presents no notch or break, though it is easily lacerated. 
The branchiz are about twenty- eight j in each fan, of con- 
siderable length, the filaments little tapered, and ending in a 
short subulate process. The pinne are comparatively short, 
but they pass to the base of the terminal process without 
apparent diminution, so that the effect is to widen the tip. 
No skeletogenous element appears in either filament or 
pinna, but the cuticle of the former is thick. 
The operculum arises by a stout pedicle on the dorsal 
edge of the left fan, which is considerably thicker than 
a branchial filament. The pedicle is flattened inferiorly, 
eradually dilates in its upward course, and then enlarges 
into the clavate operculum, which is truncated and hollowed 
out, yellowish when seen laterally, somewhat olivaceous on 
its distal surface. In lateral view the ventral outline of 
the apparatus is the more convex, the dorsal beg nearly 
straight. 
The body is widest anteriorly, the alar membrane increasing 
its bulk in this region, then tapers a little to the tail with the 
anus at the tip posteriorly. It is rounded dorsally, slightly 
flattened ventrally, where a median groove runs throughout 
the posterior region. 
Six pairs of bristle-bundles occur in the anterior region, 
as in Pomatocerus, and each has tliree fascicles. The pale 
golden bristles are a little narrowed at the insertion, have 
straight shafts, and shghtly curved tapering tips, which end 
in translucent hair-points, and with very narrow wings. 
The posterior bristles are few in number, two or three, as a 
rule, being in each foot. The shaft is slender and nearly 
cylindrical, but is narrowed below the distal enlargement, 
which forms a flattened blade with an almost transversely 
spinous distal edge, one angle of which is produced into a 
short whip or pointed process. It is remarkable how closely 
such a bristle resembles the brush-shaped forms of the 
Eunicidée and other groups. 
The anterior hooks are in single rows, very numerous and 
fairly large, but it is difficult from their translucency to 
define their exact outline. The anterior edge is nearly 
straight and saw-lhke from minute denticulations, the last 
of which (probably corresponding to the main fang) projects 
outward and downward as a minute blunt process, the body 
of the hook forming a narrow, flattened, and transparent bar. 
The crown is small and rounded, and the whole body of the 
hook is easily curved under pressure. 
