_Genus_--CHTHAMALUS.
Fig. 1 _a_, Chthamalus stellatus, shell, _var. a_ (communis).
1 _b_, " " " " _e_ (depressus).
1 _c_, " " " " _c_ (communis).
1 _d_, " " " " _d_ (fragilis).
1 _e_, " " scutum and tergum, viewed inside,
_var. c_, British.
1 _f_, " " scutum and tergum, viewed inside,
_var. a_, Madeira.
1 _g_, " " scutum and tergum, viewed inside,
_var. e_, Mediterranean.
1 _h_, " " scutum and tergum, viewed inside,
_var. c_ and _e_, St. Jago,
Cape de Verde Arch.
2, Chthamalus antennatus, shell.
3 _a_, Chthamalus dentatus, shell; 3 _b_, _var._ shell,
attached to a ship's bottom; 3 _c_, tergum, viewed from
within.
4 _a_, Chthamalus cirratus, scutum, viewed on inside; 4 _b_,
tergum, viewed on inside.
5 _a_, Chthamalus Hembeli, shell, old specimen.
5 _b_, Chthamalus Hembeli, younger shell; C, carino-lateral
compartment; _a′_, ala; _d_, radius; E, carina; _a′_, the
two alæ.
5 _c_, Chthamalus Hembeli, scutum, external view of; 5 _d_,
tergum, external view of; _e_, two of the crests, to which
the tergal depressor muscles are attached, much enlarged
and viewed from vertically beneath, showing the lateral
denticuli or sub-crests.
6 _a_, Chthamalus fissus, shell; 6 _b_, scutum and tergum,
separated, internal views of.