(_b._) A layer of chitine homologous with the shell, and
_partially_ lining the scutum.

(_c._) The inner lining (of chitine) of the sack of the
female.

(_d._) A double fold of corium.

2. _Scalpellum rutilum_, (magnified two and a half times).

2_a'._ _Scalpellum rutilum_, Internal view of scutum, enlarged.

(_a._) Depression for the adductor muscle.

(_b._) Cavity for the reception of the male.

2_b'._ _Scalpellum rutilum_, External view of carina.

2_c'._ _Scalpellum rutilum_, Section across middle of carina.

3. Complemental Male of _Scalpellum Peronii_, greatly magnified.

4. Complemental Male of _Scalpellum villosum_, greatly magnified.

(_a'._) Natural size.

4, _a, b, c._ Ditto, valves separated.

(_a._) Scutum.

(_b._) Tergum.

(_c._) Carina.

5. Complemental Male of _Scalpellum rostratum_, a restored
figure, greatly magnified. Scutum and rudimentary carina
correct.

6. _Scalpellum Peronii_, one and a half the natural size.

(_a._) Rostrum a little more enlarged, front view of.

7. _Scalpellum rostratum_, magnified six times.

(_a._) Rostrum, front view of.

8. _Scalpellum villosum_, magnified one and a half the natural
size.

8_a_, _b._ _Scalpellum villosum_

(_a._) Internal view of rostrum.

(_b._) Internal view of sub-rostrum.

TAB. VII.

Fig.

1. _Pollicipes cornucopia_, (one and a half nat. size.)

1_a._ _Pollicipes cornucopia_, internal view of valves.

2. _Pollicipes polymerus_, (one and a half nat. size.)

2_a._ _Pollicipes polymerus_, internal view of valves.

3. _Pollicipes mitella_, nat. size.

3_a'._ _Pollicipes mitella_, nat. size, internal views of

(_a._) Scutum, and of

(_b._) Tergum, showing articular fold.

3_b'._ _Pollicipes mitella_, Internal view of other valves, in a
small specimen, showing the manner in which the valves of
the lower whorl overlap each other.

(_a._) Upper latera.

(_b._) Carina,

(_c._) Sub-carina, both viewed a little obliquely.

(_d._) Rostrum,

(_e._) Sub-rostrum, both viewed a little obliquely.

4. _Pollicipes spinosus_, one and a half nat. size.

5. _Pollicipes sertus_, one and a half nat. size.

TAB. VIII.

Fig.

1. A piece of rock bored in