_Genus_--BALANUS.
Fig. 1 _a_, Balanus Ajax; 1 _b_, scutum external; 1 _c_, tergum
external; and 1 _d_, scutum, internal view.
2 _a_, 2 _b_, Balanus stultus, scutum and tergum, external
views; 2 _c_ and 2 _d_, scutum, internal and external views.
3 _a_, Balanus calceolus; 3 _b_, variety; 3 _c_, scutum,
internal view; 3 _d_, tergum, internal view; 3 _e_, spur of
tergum toothed.
4 _a_, Balanus galeatus; 4 _b_, 4 _c_, scutum and tergum,
internal view.
5 _a_, 5 _b_, Balanus cymbiformis, scutum and tergum,
internal view.
6 _a_, Balanus navicula; 6 _b_, 6 _c_, scutum and tergum,
internal view; 6 _d_, scutum, external view.
7 _a_, Balanus trigonus; 7 _b_ and 7 _c_, scutum, external
views, two varieties; 7 _d_, scutum, internal view; 7 _e_
and 7 _f_, tergum, external views, two varieties.