118 
NAUTILOIDEA. 
the termination of the first whorl, and often even as far as the ex- 
tremity of the second, after which the crenulations disappear and 
the keels become simple. 
The septa are moderately distant from each other, numbering 
about twenty-five in a complete whorl; the sutures arc straight 
throughout their whole extent. The body-chamber is large, and 
occupies about half of the last whorl. The siphuncle is relatively 
Fig. 18. 
Coelonautilus piiiguis. — a, lateral view, showing the central perforation and the 
colour-bands, indicated by the lighter shaded radiating spaces in the 
umbilicus; the serrations on the keels of the inner whorls are too fine to 
be figured ; b, front view% showing the peripheral keels. The specimen is 
a little distorted. Drawn from a specimen in the Collection. Natural size. 
large, and is situated at the superior third of the ventro-dorsal 
diameter. The test is very thin and its surface is covered with fine 
irregular lines of growth, scarcely visible to the naked eye ; their 
direction indicates that the border of the aperture was sigmoidal at 
the sides and deeply emarginate on the periphery, as in canniferiis. 
HemarTcs. De Koninck’s name having priority over M‘Coy’s, the 
latter was changed to Coy anus by d’Orbignyh The example 
which I have figured above (No. 43862) shows distinct light-coloured 
bands on the inner slope of the whorls, the traces of the colour- 
ornaments of the shell. 
The present species differs iiom paucicarinatus ( = i\h cariniferus^ 
' Prodrome de Paleont. Stratigr. 1849, vol. i. p. 111. 
