n most respects similar, to those of _P.
cornucopia_. In a specimen in which the sixth cirrus had eighteen
segments, the shorter ramus of the first pair had ten segments, of which
the five lower segments were thick and clothed with doubly serrated
spines. In the second cirrus the anterior ramus had fifteen segments, of
which the four basal ones were highly protuberant, and thickly clothed
with spines. These spines, and some on the third cirrus, and a few on
the first cirrus, have peculiar bent teeth, presently to be described
under _P. polymerus_. These singularly toothed spines are absent in _P.
cornucopia_. From the above numbers, we see that the first and second
pairs of cirri have more segments in proportion to the sixth pair, than
in _P. cornucopia_; and in the second pair, a fewer proportional number
of the basal segments are protuberant and thickly clothed with spines.

_Caudal Appendages_, shorter than the lower segments of the pedicels of
the sixth cirrus, with only four articulations; rather constricted near
the base.

The _Ovigerous Fraena_ consist of very long and prominent folds, thinning
out to nothing towards the bases of the scuta, but not furnished, as far
as I could see, with glands, and therefore not normally functional.

_Diagnosis with P. cornucopia._--The reddish-orange colour of the valves
alone suffices. There is a very slight difference, in the larger
proportional size of the upper latera, and in the outline of the basal
margin of the carina. In the maxillae there is, in _P. elegans_, a
greater width between the two upper tufts of fine spines. In the cirri,
the segments in the first pair, are more than half as many as those in
the sixth pair; in the anterior ramus of the second pair, only 4/15ths
of the segments are protuberant and brush-like, whereas in _P.
cornucopia_ 5/12ths are in this condition.

3. POLLICIPES POLYMERUS. Pl. VII, fig. 2.

POLLICIPES POLYMERUS.(!) _G.B. Sowerby._ Proc. Zool. Soc., 1833,
p. 74.

--MORTONI. (!) _Conrad._ Journal Acad. Nat. Sci. Philadelphia,
vol. vii, p. 261, Pl. xx, fig. 12, 1837.

_P. capitulo, valvarum duobus, tribus, aut pluribus sub-rostro
verticillis instructo: valvis sub-fuscis: lateribus a supremo ad infimum
gradatim quoad magnitudinem positis: carinae margine basali (introrsum
spectanti) ad medium excavato: pedunculi squamarum verticillis densis,
symmetrice dispositis._

Capitulum with two, three, or more whorls of valve