56 
NAUTILUS polygon alis. 
TAB. DXXX. 
Spec. Char. Sphaeroidal, compressed, smooth ; 
columella prominent ; umbilicus very small ; 
aperture arcuate, above half the diameter of 
the shell, long ; septa distant ; siphuncle near 
the outer edge of the septum, composed of a 
number of straight tubes. 
The thickness of this is about two-thirds of its diameter : 
it has a large aperture, the reflected extremities of which 
nearly close the umbilicus ; the septa are distant, very 
concave, and but slightly curved at their edges ; the 
siphuncle consists of a number of straight tubes, each 
projecting a little behind the septum it pierces to join 
the preceding tube. The whole series appears to be 
disjointed ; the polygon formed by it in the section has 
suggested the specific name. 
Probably from Dorsetshire. The only specimens we 
have met with were in the immense and various collec- 
tion of the late Mr. G. Humphries, along with specimens 
of N. lineatus tab. 41, marked from that county. The 
stone attached to the specimens resembles the Inferior 
Oolite. 
In N. lineatus, (which this nearly resembles,) the 
septa are numerous, the siphuncle central and curved, 
and the columella solid. 
