364 
NArilLOlDE.^. 
seems from its dcntated margin evidently intended to lireak throng! i 
hard substances, whilst the sharp edges of the heak of the Cuttle- 
fish better adapt it for cutting and lacerating the soft bodies of fi>h. 
Indeed, in the particulars just mentioned, ihe mandibles of Xautllus 
differ from those of every other known species of recent Cephalo- 
poda. There are, however, certain fossils called liJnfncholitfS^ 
formerly considered to be the beaks of fossil birds, but recognized 
by Blumenbach as appertaining rather to the Cei>haJo£>oda^ although 
Fig. 76. 
Nautilus pomjnlius. — a, front view of lower mandible showing the dentated 
margin of the calcareous upper part ; h, lateral view of the same, showing 
the widely expanded horny lamina* of this mandible ; c, lateral \iew of the 
upper mandible with its h.ood-like exiKinsion ; d, front view of the same, 
showing the limits of the calcareous extremity of the mandible on the 
underside. The calcareous e.xtremities of the mandibles are indicated in 
figures h, r, d by lighter shading, and a light irregular line shows the 
extent of the calcareous matter. This could not well be indicated in a 
without interfering with the definition of the dentated maigin. ])rawn of 
the natural size from specimens in the Geological Dciiartment, Britisli 
Museum. 
evidently differing from all the recent genera then known. ^I. 
d’Orbigny having invariably met with a large kind of these Wn/n- 
cliolites in the same stratum with the fossil shell of a large Nautilus 
(Nautilus gi(jas\ suspected from that circumstance that they might 
be the mandibles of that species (see his Memoir in the Ann. des 
Sci. Nat. V. p. 211, pi. 6). The calcareous extremities of the man- 
dibles of Nautilus imnpilius, and the peculiarities of their form, 
especially the flattened supeiior surface of the upper mandible, fully 
confirm that conjecture, and at the same time show that a small 
portion only of the beak is represented by the fossil.” 
JiemarL's. The resemblance between the calcareous extremity of 
the upper mandible of Nautilus represented in figure 76, d, 
and the corresponding fossil mandibles (figures 78, c and /; 79, cZ; 
