- Fig. 1, Entire animal (female and two males) greatly magnified, being
an unusually symmetrical specimen, partly copied from Mr.
Hancock’s Plate (‘Annal. and Mag. Nat. Hist.’ ser. 2, vol.
4, Pl. VIII).
H, horny disc and surface of attachment;
a, projection formed by the lower end of the lip of the orifice
leading into the sack;
m, a pair of males, of their proper
proportional sizes, attached in their ordinary position.
- 2, Entire animal, much distorted.
- 3, Small portion of a Fusus (copied from Mr. Hancock’s Plate),
perforated by the Alcippe; the darker curved marks are
the slit-like orifices, leading into the chambers; the latter
are seen from the outside, owing to a difference of tint in
the shell of the mollusc where worn thin over the chambers;
they are represented by the fan-shaped shaded patches.
- 4, One of the orifices, leading into a chamber, much enlarged;
a, the curved narrow end, which was open and used
when the animal was young, but has since been closed
externally by sand or shelly matter, and internally by the
upward prolongation of the horny disc;
b, rims of an inorganic, calcareous deposit, by which the narrow end of
the orifice is kept of the due degree of narrowness.
- 5, Longitudinal section through the outer envelopes of a very
symmetrical specimen, giving a lateral view of the included body.
- a, point at the lower end of the orifice of the capitulum,
leading into the sack.
- b, end of adductor muscle.
- c, mass of branching ovarian cæca, much developed and
protuberant on the under side.
- d, basal point of the quasi-peduncle, projecting beyond the
level of the horny disc (H, H).
- e, sack or open cavity: of the two branchiæ or ovigerous
fræna, one has been removed with the outer envelopes,
the other is hidden by the projection caused by the
medial distended mass of the ovarian cæca.
- e′, lateral line of junction of the body to the outer envelopes;
which latter have been here cut through in removing the
near half of the capitulum and peduncle.
- f, notch separating the capitulum or upper part from the
peduncle or lower part of the external covering: this
notch varies much in depth.
- g, the end (homologically the carinal end), of the orifice
leading into the sack, where the cutting of the outer
envelopes has commenced.
- H H, horny disc, cut longitudinally down the middle.
- h, first pair of cirri.
- i, prosoma (homologically the second thoracic segment).
- k, the thoracic segment, which would have borne the second
pair of cirri, had such existed.
- l, thoracic segment, which should have borne the third pair.
- m, thoracic segment, which should have borne the fourth pair.
- n, thoracic segment, very small, bearing the fifth pair of
cirri.
- n′, fifth pair of cirri, only one cirrus on the near side being
represented.
- o′, sixth cirrus, borne on the last thoracic segment, too small
to be shown.
- p, caudal appendages.
- 6, one side or lip of the orifice leading into the sack, greatly
enlarged, seen on the inner side, formed of an inner membrane,
b, (on which the long hairs and an S-like band of
spines, too fine to be plainly represented, are placed), and an
outer membrane c, studded with short, thick spines, the
corium between these two membranes having been removed;
a, projection at lower end of orifice;
g, upper end of orifice, showing the point where the corresponding
side or lip of the orifice has been cut away.
- 7, small portion of the external membrane, showing the star-shaped,
hard, projecting points of chitine; but they are
here placed too closely together.
- 8, front view of mouth, greatly enlarged, and with the gnathites
rather unnaturally separated from each other; h, the first
pair of cirri; in front, the outer maxillæ appear like a
bilobed lower lip; the inner maxillæ (with their singular
membranous swelling behind, see fig. 15), can be distinguished
by their long apodemes or horny imbedded
bars; behind are seen the one-toothed mandibles, with a
swelling behind, probably representing the palpi; all
above the mandibles consists of the immensely developed
labrum, with the foreshortened ends of the row of long
hairs on each side; the fold, or articulation, separating
the mouth and body, is seen crossing above the basal
ends of the apodemes of the maxillæ.
- 9, Lateral view of the coriaceous button or cushion, c′, on one corner
of the upper segment, b, of the pedicel of the sixth cirrus;
c, being the lower part of the lower segment of the one
ramus of this same cirrus: the hooked hairs are rather
distorted.
- 10, The same, viewed from the inner side.
- 11, Lateral view of the labrum, with the mandible, m, attached to
it, which latter, from overhanging the œsophagus, shows the
position of the mouth;
h h, is the first cirrus on the near side;
b, is the medial crest of labrum, on the side of which
extends a long row of hairs;
a a a, delicate membrane
of side of body, attached to the margins of the labrum.
- 12, Diagram showing the probable manner in which the young
Alcippe bores into the shell of molluscs;
a, pupa attached by the antennæ to the outer surface of shell;
b, outline of
young Alcippe soon after its metamorphosis; the anterior
or lower end has increased considerably in length, so as to
project beyond the point whence the antennæ rise, and it
has now penetrated the shell, being attached to the roof
of its incipient chamber by its horny disc, represented by
a thick black line;
c, is the Alcippe after further growth,
when it has succeeded in burying itself; the horny disc is
now attached parallel to the surface of the shell; the
horny disc of its former state, now lines the narrow end
of the slit-like orifice leading into the shelly chamber: the
above changes in position are supposed to have been
effected quite gradually. The diagram, c, I may add,
represents the position of the Alcippe for the rest of its
life, the chamber being added to at both ends, sides, and
bottom.
- 13, Lateral view of the posterior extremity of the thorax, much
enlarged, with its articulated appendages represented only
on one side;
the four thoracic segments, l, m, n, o, correspond
with those represented in fig. 5. In one monstrous
specimen, segment n, bore a single cirrus. The posterior
thoracic segment, o, bearing the sixth pair of cirri, o′, is
very small and obscure, and can be seen only by separating
the fifth and sixth pairs of cirri; or by longitudinally
bisecting the thorax, and viewing the inner side;
n′, fifth cirrus;
a, lower segment,
b, upper segment of pedicel;
c, lower, and d, upper segment of the one ramus, the
other ramus being represented by the coriaceous boss c′;
o′, sixth cirrus, with similar segments; p, caudal appendage.
- 14, First cirrus.
- 15, Maxillæ, with the lower end of the apodeme cut off, showing
the curious membranous swelling on the side towards the
mandible.