116 
AMMONITES sphericus. 
TAB. LUI.—ig. 2. 
Spec. Cuar. Orbicular, inner whorls concealed ; 
septa with four broad angular folds. Aperture 
narrow. : 
Martin Petrif. Derb. Tab. 1, Figs. 3, 4, and 5. 
ry Sg ae 
Tue diameter and thickness are nearly equal; in other 
respects the interior of this shell resembles the last. 
I could not discover the shell of this, although I -had it 
in the stone, and the specimen within was a loose part that 
was enveloped by the remainder, which seemed as large 
altogether as Fig. 1, but united by degrees with the dark 
Limestone and lost its form. It is from Derbyshire. 
AMMONITES minutus. 
TAB. LII.—Fig. 3. 
Spec. Cuar. Orbicular, inner whorls concealed 
with many distant longitudinal strie. Aperture 
lunate. 
Se a 
"Tuickness and diameter nearly equal. Stria about 
twenty-four. Aperture rounded at the sides, It has a 
small umbilicus. Diameter two or three lines. 
Apparently a minute species of this Genus, but being a 
cast in Pyrites it only exposes the pattern of the external 
part of the shell and the aperture. From Folkstone in 
Kent, by favour of Mr. Gibbs. The right hand figure is 
the natural size, the other magnified. It looks at first 
sight like a very young specimen of Ammonites sublevis, 
tab. 54: that, however, was far from being so orbicular 
when in a young state. 
