PROOFS OF DESIGN IN AMMONITES. 
355 
Conclusion. 
On examining the proofs of Contrivance and 
I^esign that pervade the testaceous remains of the 
family of Ammonites, M'^e find, in every species, 
abundant evidence of minute and peculiar me- 
chanisms, adapting the shell to the double pui- 
Pose of acting as a float, and of forming a pro- 
jection to the body of its inhabitant. 
As the animal increased in bulk, and advanced 
^long the outer chamber of the shell, the spaces 
left behind it M^ere successively converted into air 
chambers, simultaneously increasing the power 
ef the float. This float, being regulated by a 
pipe, passing through the whole series of the 
chambers, formed an hydraulic instrument of 
extraordinary delicacy, by which the animal 
smooth and rounded upwards towards the body of the 
Animal, (PI. 38, S. S.), and thus the jagged terminations of 
’■I'ese lobes may have afforded holdfasts whereby the base of the 
*“antle could fix itself firmly, and as it were take root, around 
bottom of the external chamber. 
^o such dentations exist in any species of Nautilus. In the 
Pompilius, Mr. Owen has shewn that the base of the mantle 
^'Iberes to the outer shell, near its junction with the transverse 
plate by means of a strong horny girdle ; a similar contrivance 
probably existed also in all the fossil species of Nautili. The 
sides of the mantle also of the N. Pompilius arc fixed to the 
sides of the great external chamber by two strong broad lateral 
""tscles, the impressions of which are visible in most specimens 
tfiis shell. 
