of the inhabitants of many species of fossil Nautili, and Ammonites, by the abundance of fossil bodies called Rhyncholites, or beak-stones, in many strata that contain these fossil shells, e. g. in the Oolite of Stonesfield, in the Lias at Lyme Regis and Bath, and in the Muschelkalk at Luneville.
As we are warranted in drawing conclusions from the structure of the teeth in quadrupeds, and of the beak in birds, as to the nature of the food on which they are respectively destined to feed, so we may conclude, from the resemblance of the fossil beaks, or Rhyncholites. (Pl. 31, 5—11,) to the calcareous portions of the beak of the Cephalopod, inhabiting the N. Pompilius, that many of these Rhyncholites were the beaks of the cephalopodous inhabitants of the fossil shells with which they are associated; and that these Cephalopods performed the same office in restraining excessive increase among the Crustaceous and Testaceous inhabitants of the bottom of the Transition and Secondary seas, that is now discharged by the living Nautili, in conjunction with the carnivorous Trachelipods.[1]
Assuming, therefore, on the evidence of these analogies,
that the inhabitants of the shells of the fossil Nautili and
Ammonites were Cephalopods, of similar habits to those of
the animal which constructs the shell of the N. Pompilius,
we shall next endeavour to illustrate, by the organization
and habits of the living Nautilus, the manner in which these
fossil shells were adapted to the use of creatures, that sometimes
formed of the same hard calcareous substance as its point; this substance is of the nature of shell.
These calcareous extremities of both mandibles are of sufficient strength to break through the coverings of Crustacea and shells, and as they are placed at the extremity of a beak composed of thin and tough horn, the power of this organ is thereby materially increased.
In examining the contents of the stomach of the Sepia vulgaris, and Loligo, I have found them to contain numerous shells of small Conchifera.
- ↑ See p. 192.
