n (as in _C. virgata_) on the peduncle,
these bands becoming more or less confluent on the capitulum; at other
times, the capitulum is more or less spotted, or often nearly uniformly
purple: the sack, cirri and trophi are, also, purple.

_Size._--The largest specimen which I have seen was, including the
peduncle and ears, five inches in length, the capitulum itself being
rather above one inch in length, and 7/10ths of an inch in breadth.

_General Remarks._--I have come to the same conclusion with Prof.
Macgillivray, concerning the variability of this form, and I believe
there is only one true species. With respect to Dr. Coates's species,
viz., _Otion depressa_ and _O. saccutifera_, though I have not seen
specimens, I can hardly doubt, from the insufficient characters given,
that they are mere varieties.

With respect to the ear-like appendages, we shall presently see in _C.
virgata_, that at corresponding points on the capitulum (Tab. III, fig.
2 _b_), there are two slight, closed prominences. According to Professor
Macgillivray, in _C. aurita_, every gradation can be followed by which
the appendages, at first closed, become tubular and open. The opening
would ensue, if the corium became absorbed at the bottom of the
appendages whilst still imperforate, for then the inner tunic would be
cast off at the next moult and would not be re-formed, whilst the outer
membrane would gradually disintegrate together with the other external
parts of the capitulum, and not being re-formed at this point, an
aperture would at last be left. These appendages have no relation to the
generative system: the ovarian tubes, which surround the sack do not
extend into them; nor do the ovigerous lamellae. I believe, that their
function is respiratory: the corium lining them is traversed by
river-like circulatory channels, and their much-folded, tubular and open
structure must freely expose a large surface to the circumambient water.
Why this species should require larger respiratory organs than any
other, I know not. In this species, moreover, the filamentary appendages
are developed to a greater extent than in any other cirripede; in most
genera, the surface of the body and of the sack suffices for
respiration.

2. CONCHODERMA VIRGATA. Pl. III, fig. 2. Pl. IX, fig. 4.

LEPAS VIRGATA. _Spengler._ Skrifter Naturhist. Selbskabet., B. i,
1790, Tab. vi, fig. 9.

---- CORIACEA. _Poli._ Test. utriusque Sicil., Pl. vi, fig. 20,