a, or between the clefts left by them; on each
side of the notch there is a slight prominence. In some few cases,
however, there is no trace of this notch. Behind the terga or the
clefts, the great ear-like appendages, as we have seen, are situated.

_Carina_, rudimentary (fig. 4) and often absent; it is
pointed-elliptical, and is rarely above the 1/40th of an inch long.
After arriving at this full size, calcareous matter is added to the
under surface over a less and less area, so that it becomes internally
pointed, and finally, in place of calcareous matter, continuous sheets
of chitine are spread out beneath it; hence, during the disintegration
of the outer surface, the carina comes to project more and more, and at
last drops out; subsequently, even the little hole in which it was
imbedded, disintegrates and disappears.

_Peduncle_, cylindrical, distinctly separated from the capitulum, and
generally twice or thrice as long as it: the thickness of the outer
membrane generally great, but variable: surface of attachment variable,
either pointed, or widely expanded, or formed into divergent
projections.

_Filamentary Appendages_, seven on each side, highly developed, long and
tapering; there are two beneath the basal articulation of the first
cirrus, and one on the posterior margin of the pedicel of each cirrus,
excepting the sixth pair; the filaments on the pedicels are nearly twice
as long as the cirri themselves.

_Mouth_,--mandibles, with the five teeth nearly equidistant, and towards
their bases finely pectinated on both sides; inferior angle rudimentary,
often represented by a single minute spine: in one specimen, there were
only four teeth on one side. Maxillae, with five steps, not very distinct
from each other, with the first step much curved. The larger of the two
upper great unequal spines is pectinated, like the teeth of the
mandibles; there is a third long finer spine beneath the upper large
pair.

_Cirri_ rather short, broad, with the anterior faces of the segments
protuberant, especially those of the first cirrus and of the anterior
ramus of the second pair: spines on the anterior cirri doubly serrated.
Posterior cirri, with the intermediate spines between the pairs, long;
dorsal tufts, minute. On the lower segment of the pedicels of the four
posterior cirri, there are two separate tufts of bristles.

_Colours_ extremely variable; sometimes five longitudinal bands of dark
purple can be distinctly see