169 
AMMONITES variant 
TAB. CLXXVT. 
Spec. Char. Depressed, thickish, carinated, with 
a row of large tubercles near the front, and 
one or two rows of tubercles placed upon fur- 
cate radiating undulations ; inner whorls half 
concealed ; aperture roundish. 
No Ammonite is more variable than this in the strength 
of the undulation, and proportion of the tubercles ; still, 
however, it may be known by the large turbercles near 
the front (these are sometimes flatted obliquely) and two 
lesser ones upon each radius near the commencement of 
it, the inner of which is generally smallest, and at times 
even obscure, or united to the other. The whorls are 
seldom more than three : the keel is much relieved, and 
entire. The length and breadth of the aperture are about 
equal to each other, and one-third the diameter of the 
shell. 
So frequently are the casts of this handsome shell dis- 
torted, as if by the compression of the chalk, while in a 
soft state, of which they are composed, that specimens 
have often been exhibited in proof of the existence of el- 
liptical Ammonites ; but a series may easily be obtained, 
some individuals of which are circular ; others com- 
pressed obliquely, and in such various directions, as to 
evince the effect of accident. The lower or hard chalk 
is well characterized by this fossil, as it contains it in 
