Fig. 1, Antenna of the pupa (three terminal segments of), with
a portion of one of the two threads, enclosing the
cement-ducts, by which the body of the Proteolepas is
attached; the upper portion of the thread, and the
adjoining part of the body, are represented in section.
_a_, part of the great mass of cellular matter within the
ovarian sack, in process of development into ova, and
changing its character as soon as it enters the tube or
cement-duct.
_b_, membrane forming the ovarian sack and the cement-ducts,
the latter enclosed within the threads of attachment.
_c_, corium lining the outer membrane of the body, and the
upper part of the threads.
_d_, outer membrane of body.
_e_, " " becoming suddenly thicker where
forming the outer membrane of the thread.
_e′_, outer membrane of the thread in the lower part, here
not shown in section.
_f_, main or second segment of the pupal antenna, the basal
segment having, as in all cases, been moulted, with the
carapace of the pupa.
_g_, disc-segment, apparently with a small orifice for the
issuing of the cement.
_h_, terminal segment with the shorter spines broken off.
2, Compounded mandibular organ, sketched by the camera; _a_,
supposed mandible; _b_, perhaps portion of the mandible;
_c_, maxilla; _d_, ligamentous fibres giving attachment to
muscles.
3, Mouth seen from the ventral side, sketched by the camera;
_r_, articulation separating the mouth from the body;
_c_, compounded mandibular organ; _d_, palpus, united to
the opposite palpus and to the crest of the labrum; the
latter forming the back of the hollow in which the compound
mandibles work.
4, Diagram of the mouth of an ordinary cirripede, seen from
above; _a_, outer maxilla; _b_, maxilla; _c_, mandible;
_d_, labrum.
5, Diagram, illustrating the supposed changes in _position_ of
the gnathites in Proteolepas, causing them to stand back
to back; _a_, outer maxilla; _b_, maxilla; _c_, mandibles;
_d_, labrum.