Mouth._--Palpi with their ends square and truncated; thickly clothed
with long spines.

_Mandibles_, with fully twice as many pectinations, (viz. from 16 to
20,) between the first and second main teeth, as between (viz. 8 to 10)
the second and third main teeth. Inferior angle, coarsely pectinated.
The distance between the tips of the first and second teeth, is
considerably less than between the tip of the second tooth and the
inferior angle.

_Maxillae_, with the edge very slightly irregular; beneath the two great
upper spines there is a slight notch, with some small spines: inferior
angle slightly prominent, with a brush of moderately fine spines;
besides these, there are about seventeen pairs of large spines; sides
very hairy.

_Outer Maxillae_, with the inner margin slightly concave, and with the
spines continuous.

_Cirri._--The segments in the three posterior pairs support three or
four pairs of long spines, with a single row of moderately long
intermediate spines; the dorsal tufts consist of a few rather thick, and
some long and thin spines. The front of the segments is not protuberant;
the whole surface is hirsute with minute comb-like scales. _Second
cirrus_, with the anterior ramus having its eight basal segments highly
protuberant and thickly clothed with spines, the upper nine having the
usual structure; the posterior ramus has four or five basal segments
thickly clothed with spines, and the twelve upper ones with the usual
structure. _Third cirrus_, with the anterior ramus having six segments
highly protuberant and thickly clothed with bristles, and the fifteen
upper ones on the usual structure; in the posterior ramus, only three or
four of the basal segments are paved with bristles. The spines on the
first three pairs of cirri, are coarsely and doubly serrated.

The _Caudal Appendages_ are more than twice as long as the pedicels of
the sixth cirrus, and equal half the length of the whole cirrus. In a
specimen in which the sixth cirrus contained twenty-two segments, the
caudal appendages actually contained twenty. The segments are thin, with
their upper edges clothed with serrated spines. The slip of membrane on
each side, whence this organ springs is united, for a little space, to
the lower segment of the pedicel of the sixth cirrus.

_Size and Colour._--Width of the capitulum rather above 4/10ths of an
inch; length, including the peduncle, (contracted by spirits,) nearly
one inch. Valves, as usual,