56 
NAUTILUS polygonalis. 
TAB. DXXX.. 
Spec. Cuar. Spheroidal, 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. 
———— a 
Tue 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. 
