5D 
AMONITES giganteus. 
RABWOCXAV I: 
+) 
Simplegades. Montfort, p. 92. 
Spec. Cuar. Depressed, with many radiating, 
sometimes furcate undulations; inner whorls 
exposed ; sides straitish ; mouth obovate. 
Var. g. Mouth nearly circular, sides rounded. 
Syn. ——— Lister, pl. 1046. 
Tear are about 5 distinct whorls in most specimens, 
the interior ones being almost wholly exposed; the septa 
are rather numerous with their margins much sinuated. 
Thickness of var. a equal to about one fourth of the 
diameter, and rather more in var. £. 
_ Tt was at a loss how to represent this, which in mag- 
nitude and beauty is preserved so many ways for our 
wonder, instruction, and gratification. It is sometimes 
filled with small grained Limestone: sometimes the 
chambers are lined or filled with crystallized Carbonate of 
Lime; the crystals being commonly equiaxed or inverse 
rhombs (see British Mineralogy tab. 12.) Such are found, 
I believe, near Keynsham, and cut and polished, thus 
shewing the chambers within, and -the sinuated margins 
of the septa, at various depths externally; they are often 
cut so thin as to be transparent in parts; my late es- 
teemed friend, Dr. Lettsom, presented me with some 
specimens of this kind, which surpass description. The 
flint that occurs in the Limestone where these shells 
abound, occasionally envelopes some of them, the cham- 
