G. 0. Orick—Gigantic Cephalopod Mandible. 261 
certainly Bradford Abbas, or the immediate neighbourhood, and that 
the specimen is of Bajocian age. 
The fossil (Fig. 2) is obviously the calcareous portion of the upper 
mandible of a giant Mauwtilus-like animal, as a comparison with that 
structure in the recent Nautilus pompilius shows. 
The mandibles of Wautilus pompilius (see accompanying figures) 
were described by Sir Richard Owen’ as follows :— 
cw a 
Fic. 1.—Nautilus pompilius. a, inner view of lower mandible showing the 
dentated margin of the caleareous upper part; 6, lateral view of the same 
showing the widely-expanded horny lamine of this mandible; c, lateral 
view of the upper mandible with its hood-like expansion ; d, inner view of 
the same, showing the limits of the calcareous extremity of the mandible 
on the inner side. The calcareous extremities of the mandibles are 
indicated in figures b,c, d by lighter shading and a light irregular line 
showing the extent of the calcareous matter. This could not well be 
indicated in a without interfering with the dentated margin. Natural 
size. (After A. H. Foord, Cat. Foss. Ceph. Brit. Mus., pt. 2, 1891, 
fig. 76, p. 364.) 
‘hese are two in number, having a vertical motion, and 
resembling in form the bill of the Parrot reversed, the upper 
mandible being encased in the lower when closed ; they are adapted 
posteriorly to a muscular basis, to which they owe their motions. 
Thus far they resemble the mandibles of the Dibranchiate 
Cephalopods ; but they are not composed entirely of horny matter, 
nor are they uniformly of a brown or black colour, their extremities 
being of a dense calcareous nature, and of a blueish white colour; 
they are also less pointed at the end; and the oral margins of the 
lower mandible are notched and dentated. 
‘They are proportionately larger than in the Cuttle-fish, each 
mandible measuring in length one inch and three lines, and in 
vertical breadth one inch. About half an inch from their anterior 
extremities the horny part separates into two lamine, the exterior of 
which in the upper mandible is of little extent (from three to four 
lines), and is dilated and flattened above so as to form a triangular 
surface half an inch broad at the base. In the lower mandible the 
proportions of the two lamine are reversed, the exterior one being 
produced to the full extent, so as to make it appear larger than the 
upper mandible, which is not really the case. 
‘The calcareous extremities of both mandibles are of a hardness 
apparently adequate to break through the densest crustacean 
1 R. Owen, Memoir on the Pearly Nautilus (Nautilus pompilius), 1832, 
pp. 20 et seqq. 
