78 



NAUTILUS radiatus. 

 TAB. CCCLVI. 



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. 



