262 8G. C. Crick—Gigantie Cephalopod Mandible. 
coverings, or even shells of moderate thickness. That of the upper 
mandible is sharp-pointed, and solid to the extent of five lines from 
the extremity; but in the lower one the calcareous matter is 
deposited on both sides of a thin layer of the black horny substance 
and thus a combination of tough with dense matter is obtained, which 
much diminishes the liability to fracture. This mandible is also 
more hooked than the upper one, but is more obtuse at the end; it 
seems from its dentated margin evidently intended to break through 
hard substances, whilst the sharp edges of the beak of the Cuttle-fish 
better adapt it for cutting and lacerating the soft bodies of fish. 
Indeed, in the particulars just mentioned, the mandibles of Wautilus 
differ from those of every other known species of recent Cephalopoda.” 
When found fossilised, usually only the calcareous extremities are 
preserved, although occasionally portions of the horny substance are 
found associated with them.! 
The present fossil is represented of the natural size in the 
accompanying figures, and a comparison of them with corresponding 
figures of the upper mandible of the recent Nautelus pompilius at 
once reveals the true nature of the fossil; thus, Fig. 2b corresponds 
to the tip of Fig. 1c, and Fig. 2c corresponds to the uppermost 
portion of Fig. 1d. 
A series of papers on the mandibles of Fossil Cephalopoda has 
comparatively recently been published by Dr. Alfred Till,’ but the 
present specimen appears to differ from all the forms belonging to 
Nautilus-like Cephalopods that have already been described and is 
therefore regarded as new. Following Dr. Till’s system of nomen- 
clature the specimen may be named Wautilus (Rhyncholithes butleri, 
n.sp.) sp., signifying that the name of the mandible is Rhyncholithes 
butlert and that it belonged to a Wautilus-like Cephalopod of which 
the species has not been determined. 
The present fossil consists almost exclusively of the fossilised 
calcareous portion of an upper mandible, but it is much larger than 
any other specimen in the British Museum collection. It bears some 
remnants of the horny substance of the mandible. In the recent 
Nautilus pompilius (see Fig. 1c, d) the calcareous portion of the 
upper mandible consists of a hood-shaped upper portion supported 
below. by a ‘shaft’. On the inner side the surfaces of these two 
portions are continuous and more or less in the same plane, but on 
1 See A. H. Foord, Cat. Foss. Ceph., Brit. Mus., pt. 2, 1891, fig. 79a 
(p. 368) and figs. 800, c (p. 369). 
2 Tritt (Alfred), ‘‘ Die Cephalopodengebisse aus dem schlesischen Neokom”’ : 
Jahrb. d. k.k. geol. Reichsanst., Wien, Bd. lvi, 1906, pp. 89-154, pls. iv, v, 
text-illust. 
Tin (Alfred), ‘‘ Die fossilen Cephalopodengebisse’’: Jahrb. d. k.k. geol. 
Reichsanst., Wien, Bd. lvii, 1907, pp. 535-682, pls. xii, xiii, text-illust. 
Tiuu (Alfred), ‘‘ Die fossilen Cephalopodengebisse’’: Jahrb. d. k.k. geol. 
Reichsanst., Wien, Bd. lviii, 1908, pp. 573-608, pls. xix (i), xx (ii), text- 
illust. 
Triu (Alfred), ‘‘ Die fossilen Cephalopodengebisse ’’: Jahrb. .d. k.k. geo!. 
Reichsanst., Wien, Bd. lix, 1909, pp. 407-26, pl. xiii, text-illust. 
Trib (Alfred), ‘‘ Uber einige neue Rhyncholithen’’: Verhandl. d. k.k. geol. 
Reichsanst., Wien, 1911, pp. 360-5, text-illust. 
