EEPORT ON THE ANNELIDA. 
11 
towards its posterior border and having a basal segment and an elongated terminal region, 
which is purplish-brown throughout, wdiereas the former region is less deeply coloured, 
with a pale band in front. From the base of the process a fan-shaped patch of pigment 
extends downward and inward on the bristle-papilla. The ventral cirrus is quite pale, 
and lies below and rather behind the ventral tuft of bristles. A slight enlargement of 
the base occurs anteriorly. The cirrus is filiform, tapering, and considerably shorter than 
the dorsal. 
About thirty-two pairs of arborescent branchise are ranged along the dorsum, the 
number var5dng according to the length of the specimen. Each is situated at the 
posterior border of the segment, a short distance from the cirrus, and slightly overlapped 
by the radiating dorsal bristles. Their shape is dendritic ; a central stem rising from the 
dorsum and giving off, first, a large external branch, which generally divides into two, and 
these give off others, which bear the ultimate pinnules. The other branches of the main 
stem pass off transversely (nearly opposite in arrangement) and subdivide into pinnules. 
Those at the tip are simple, i.e., have no subdivisions. In the ordinary condition the 
branchiae fold backward, and since the pinnules are all grouped posteriorly they are thus 
in the most protected position. In minute structure the stem' consists externally of a 
firm cuticular investment, a considerable layer of hypoderm, a -central area of muscular 
and connective tissue, and the two main vessels (afferent and efferent). Each of the 
ultimate pinnules also carries its two blood-vessels in the midst of a considerable amount 
of hypoderm. The muscular fibres in the centre of the main stem are complex- 
longitudinal and radiating as well as transverse. If a longitudinal section of any of the 
larger branches be made, the tranverse fibres form a series of septa. 
The branchise continue to the penultimate segment, but diminish in size posteriorly. 
They are marked by a deposit of pigment, best seen in small specimens, along the 
main branches. 
The dorsum of the animal has a very conspicuous row of brownish-purple spots, 
which occupy the posterior two-thirds of each segment, in the middle line. A brownish 
band also occurs at the anterior part of each segment, from the branchise outward. The 
anus is dorsal, with two elongated cirri behind it. 
When withdrawn the proboscidian region presents three layers — an outer membranous, 
a denser middle portion, and an inner division of cartilaginous consistence. The latter 
forms two longitudinal folds, which in extrusion become transverse. In the quiescent 
state of the parts {i.e., when withdmwn) in the Mediterranean Chloeia procured during 
the “Porcupine” Expedition, the lining tissue of the buccal cavity forms some simple 
folds superiorly, above the two muscular external lips. These folds gradually increase in 
complexity, and when the lips disappear they form a series of vertical and horizontal 
papillae. The latter are covered by the usual dense cuticle, with h}q)oderm beneath, 
and followed by a complex muscular layer varying according to the situation examined 
