51 
NAUTILUS obesus. 
TAB. CXXIV. 
Spec. Cuar. Gibbose, umbilicate, plain; back 
broad, flat; mouth large, squarish ; septa 
very numerous, not recurved ; siphuncle nearly 
central. 
Tarcxnzss about three-fourths the diameter. The 
mouth is large, being two-thirds the diameter long. The 
septa are very numerous ; their angles not being recurved 
gives a very open form to the umbilicus. The siphuncle 
is transversely oval. 
My kind and discerning friend Mr. Strangewayes sent 
me this from the coarse or rather ferruginous limestone, at 
Norton-under-ham ; it is often of a large size (a foot or 
more long) and clumsy make, but seldom perfect. It is 
readily distinguished at first sight by the flat broad back, 
and afterwards by the siphuncle being nearly in the 
middle of the septa, inclining inwards: both these cha- 
racters being taken together will distinguish many species, 
yet I expect more may be occasionally necessary. The 
shell must have been very thin and without peculiar 
markings, as there is no sign betwixt the curve and the 
mouth that betrays any. ‘The divisions are sometimes 
irregular, but that happens in the most perfect in many 
other species. 
