78 
NAUTILUS radiatus. 
TAB. CCCLYI. 
Spec. Char. Gibbose, umbilicated ; surface 
marked with curved, radiating undulations ; 
sides and front rounded ; aperture orbicular, 
deeply indented. 
A species intermediate between N. elegans and undu- 
latus. It is more regularly convex, and has more un- 
dulations than the latter, as many as four or five to each 
septum, but not near so many as occur in the former. 
The length and breadth of the aperture are nearly equal 
and exceed half the diameter of the shell. I am not 
acquainted with the situation of the siphunculus. The 
waves upon the surface are most elevated, and meet 
from the sides upon the front at an obtuse angle. 
Lately found in the neighbourhood of Maltor, proba- 
bly in the lower part of the Green Sand formation. I 
have received but one specimen, a cast in Marly Lime- 
stone, mixed with grains of Silex and of blackish Green- 
earth. The umbilicus is so open as to shew the inner 
whorls and the edges of the septa very beautifully. It 
is possible that if the shell had remained, the umbilicus 
would have been filled, but in that case the shell must 
have been very thick, so I have ventured to describe it 
as open. 
