137 
NAUTILUS sulcatus. 
TAB. DLXXI.—figs. 1. & 2. 
Spec. Cuar. Discoid, minutely striated ; whorls 
almost wholly exposed, ventricose, with two 
large furrows on each side and several small 
ones ; front concave. 
Onzs of the remarkable furrows that modify the form of 
the whorls of this shell is concealed in the inner turns ; 
the concave front is bounded by sharp edges; there is 
also a sharp elevation between the two furrows: the 
rest of the side is gibbose, with two or three very shal- 
low broad furrows upon its most elevated part. The 
aperture is half as long again as it is wide, its sides of 
course indented: the siphuncle is placed just opposite 
to the inner indentation ; the septa are numerous, with 
even edges. 
Occurs in the Mountain Limestone. We have met 
with two or three specimens in the late Mr. G. Hum- 
phreys’s collection, labelled by him as having been found 
at Castleton. 
Fig. 1. shows a cast of the inside. Fig. 2. the exter- 
nal surface of the shell. 
