istinct rounded
swelling with bristles. The olfactory orifices are highly protuberant,
approximate, flattened, scarcely tapering towards their upper ends.

_Cirri._--The five posterior pair are elongated, very little curled,
with short pedicels; their segments are long, not at all protuberant in
front, bearing five or six pairs of long, slightly serrated spines, with
a very minute tuft of bristles between each pair, and with some short
lateral spines on the inner side of each segment; on the fourth pair of
cirri, these lateral spines are considerably developed; dorsal tufts
consist of fine spines, with one much longer than the others. _First
pair_ short, separated by a wide interval from the second; rami unequal
in length, by between two and four segments; longer ramus having nine
segments, scarcely half as long as the rami of the second cirrus;
shorter ramus with seven segments; in the same individual there were
twenty segments in the sixth cirrus. The segments in the shorter ramus
of the first cirrus are oblong in a transverse direction, and may be
compared to a set of shields placed transversely and strung together; in
the longer ramus the segments are longitudinally oblong; in both they
are thickly covered with spines. _Second cirrus_; the anterior ramus is
a little broader than the posterior ramus, with the segments bearing
about five rows of bristles; fifteen segments in the shorter ramus.
_Third pair_, with the two rami equal in thickness, and with the
segments differing very little from those of the posterior cirri,
excepting that the serrated spines in the external lateral rows are
rather larger. The fourth pair is remarkable by having, on the inner
side of the upper edge of each segment, a little tuft of minute smooth
spines, flattened, and a little enlarged near their ends, so as to be
spear-shaped; I could not see these singular spines on the other cirri.
The lower segments of the pedicels of all the cirri, excepting the sixth
pair, are remarkable from having their inner edges, in the middle,
produced into a considerable, abrupt, rounded projection, irregularly
covered with spines.

_Caudal Appendages_, (Pl. X, fig. 21,) very small, flattened, of nearly
the same width throughout; in a medium-sized specimen, only 1/100th of
an inch in length; each bears from ten to twenty small bristles placed
distantly from each other, of which those on the rounded apex are the
longest.

_Generative System._--The penis is