the labrum.

6. _Anelasma squalicola._ The right-hand, rudimentary cirrus, the
third from the mouth.

7. _Anelasma squalicola._ Maxillae. The thin horny apodeme, (_a_).

8. _Ibla Cumingii_, female, (magnified four times.)

8_a'._ _Ibla Cumingii_, female, (magnified about five times), with
the right hand valves and right side of the peduncle
removed. The Male (_h_) is seen attached in the sack. The
peculiar form of the body, caused by the small development
of the prosoma, by the distance of the first and second
pairs of cirri, and by the distance of the mouth from the
adductor muscle, (a dark dotted circle opposite _i_,) and
lastly, the remarkable course of the oesophagus over the
adductor muscle, together with the outline of the stomach,
are here all exhibited.

(_a._) Scutum; the end of the large rounded adductor
muscle, which was attached to the valve now removed,
near its apex, is plainly seen.

(_b._) Tergum.

(_c._) On a line with this letter, is seen the largely
bullate labrum, forming a blunt overhanging projection.

(_d._) Palpus, close to the upper segment of the pedicel of
first cirrus.

(_e._) Orifice of the acoustic (?) sack, between the bases
of the first and second cirrus.

(_f._) Caudal appendages.

(_g._) Branching ovarian tubes within the peduncle.

(_h._) Male, on the same scale, lying in its natural
position within the sack, with the lower part of its
peduncle bent upwards, and imbedded in the corium and
muscles of the female.

(_i._) Adductor scutorum muscle.

8_b'._ _Ibla Cumingii_, Internal view of the scutum and tergum,
and of the upper part of the outer integument of the
peduncle, with its horny spines magnified about three
times.

8_c'._ _Ibla Cumingii_, A small portion of the outer integument of
the peduncle, greatly magnified, showing the horny
persistent spines; two of the spines have been torn out.

9. _Ibla quadrivalvis_; internal view of scutum and tergum, and of
the upper part of the outer integument of the peduncle;
magnified four times.

9_a'._ _Ibla quadrivalvis_, Penis supported on a long
unarticulated projection; greatly magnified.

TAB. V.