89 
NAUTILUS pentagonus. 
TAB. CCXLIX.— Fig. 1 . 
Spec. Char. Discoid, subcarinated ; inner turns 
partly concealed ; aperture orbicular, obscure- 
ly 5-angled, and impressed by the preceding 
whorle, nearly half the diameter of the shell 
long. 
Besides the carinated form of the front of the whorle 
it is flattened a little upon each side, which gives five 
inconspicuous angles to the aperture. The turns are 
few, and increase rather rapidly in size, the inner ones 
being about one-third covered by the outer. The septa 
are not very concave, rather numerous, with a central 
siphuncle. The surface is apparently smooth. The 
young shells seem to be less angular than the older 
ones. 
The first specimen I received of this Nautilus was 
found in black Limestone, at Bathgate, Scotland, and 
given to me by my friend Dawson Turner, Esq. I lately 
received several specimens in red Limestone, from the 
same quarries at Closeburn which produced the gigan- 
tic Orthocera, tab. 246. through the liberality of C. S. 
Menteith, Esq. They are probably what Jameson has 
spoken of as large Ammonites. I do not know they 
are found much larger than the figure. 
NAUTILUS bilobatus. 
TAB. CCXLIX.— Figs. 2 and 3. 
Spec. Char. Subglobose, umbiiicated ; septa two- 
lobed ; aperture 3 or 4 times as wide as long. 
A nearly globose shell, with the front a little flattened, 
the umbilicus is small and nearly cylindrical ; the si- 
