- Fig. 1 a, Chthamalus intertextus, shell;
1 b, scutum and tergum, calcified together, with the suture obliterated in the upper part,
internal view of.
- 2 a, Chthamalus scabrosus, shell;
2 b, scutum, internal view of;
2 c, tergum, internal view,
p, plate forming one side of the cavity in which the depressor muscle is attached;
2 d, tergum, as seen from almost vertically beneath;
p, pit for the depressor muscle;
q, special pit for the lateral, properly scutal depressor muscle;
r, articular furrow.
- 3 a, Chamæsipho columna, shell;
A, rostrum;
B, lateral compartment, probably formed by fusion of the rostro-lateral
and lateral compartments;
E, carina;
3 b, 3 c scutum and tergum, internal views of.
- 4 a, Chamæsipho scutelliformis, shell much enlarged, seen from above;
A, rostrum, separated by imperfect sutures from the
(B) lateral compartments, which are formed probably
by the fusion of the rostro-lateral and lateral compartments;
E, carina;
B stands opposite one of the inward
folds of the wall, leading into one of the tubular apertures,
which runs (generally with an irregular spiral curve)
through the whole thickness of the shell down to the surface
of attachment. The carina has two of these apertures.
- 4 b, Chamæsipho scutelliformis, another specimen, seen from the under side,
letters of reference the same.
- 4 c, Chamæsipho scutelliformis, rostrum, disarticulated, enlarged, showing the alæ.
- 4 d, Chamæsipho scutelliformis, scutum and tergum, internal views of.
- 5 a, Pachylasma giganteum;
5 b, rostrum of an extremely young specimen, much enlarged, showing its
compounded nature, viz., of a true rostrum and rostro-lateral compartments;
5 c, scutum and tergum, external views of;
5 d, scutum and tergum, internal views of.