109 
NAUTILUS complanatus. 
TAB. CCLXT. 
Sp. Char. Discoid, compressed, smooth ; sides 
flat ; inner turns exposed ; aperture lance- 
olate. A reversed sinus in the edge of each 
septum, near the inner angle. 
The margin is rounded, but the sides very flat;* 
the inner volutions are completely exposed by a kind of 
truncation of the inner edges of the whorles, the surface 
left by this truncation is concave. The whorles are 
about four or five; half of the last is free from septa ; the 
length of the mouth is 5 or 6 times its width. 
This Nautilus appears to be entirely new; it was dis- 
covered in a slaty Limestone, at Scarlet, on the Isle of 
Man, by J. S. Henslow, Esq. This gentleman promises 
to give a more perfect geological account of the Isle of 
Man, than has hitherto appeared, and to correct many 
false ideas that have been circulated respecting it. 
* I suppose this to be the original form, and not ascribable to the pres- 
sure of the Slaty Stone. 
