SHELLS ALLIED TO NAUTILUS. 361 
It is a curious fact, that contrivances, similar 
to those which existed in some of the most early 
forms of Ammonite, should have been again 
adopted in some of the most recent species of 
fossil Nautili, in order to afford similar com. 
pensation for weakness that would otherwise 
have been produced by aberrations from the 
normal structure of the genus Nautilus. All 
this seems inexplicable on any theory which 
would exclude the interference of controlling 
Intelligence. 
SECTION VI. 
CHAMBERED SHELLS ALLIED TO NAUTILUS 
AND AMMONITE. 
We have reason to infer, from the fact of the 
recent N. Pompilius being an external shell, 
that all fossil shells of the great and ancient 
family of Nautili, and of the still more nume- 
rous family of Ammonites, were also external 
shells, inclosing in their outer chamber the body 
and of N. Zic zac ; like them also the margin was simple and 
destitute of fringed edges. The A. nodosus (PI. 40, Figs. 4 and 
6.), which is peculiar to the early Secondary deposits of the Mus- 
chel-kalk, offers an example of an intermediate state, in which 
the fringed edge is partially introduced, on the descending or 
inward portions only, of the lobated edge of the transverse plates. 
