21 
TAB. CCCCXX. 
AMMONITES Catena. 
Spec. Char. Depressed, furnished with two 
rows of short tubercles upon each side ; 
whorls 6 or 8 smooth, with flat sides, the 
inner ones exposed ; front rather convex ; 
aperture square. 
So seldom is any more than the casts of the chambers 
of this shell found that its true form is scarcely known ; 
these casts have, by the decay of their surfaces, lost so 
much that they hang loosely together, like the links of 
a chain : when less diminished, they are found adhering 
but with very slight traces of the shell remaining ; it 
appears to be smooth, and to have no undulations or 
ribs excepting when very young : the tubercles are 
upon the inner and outer angles of the flat sides of 
the whorls ; they are of a moderate size, conical, with 
rounded points, and are not truncated in the cast : the 
edges of the septa are very much, deeply and sharply 
sinuated ; the front is slightly rounded, without any ap- 
pearance of a keel. 
A long known, and highly admired relic of the ancient 
world ; the casts of the chambers hanging loosely to- 
gether have an imposing appearance. It seems that 
this shell was first lined with a sparry crust, containing 
much Iron, and afterwards filled up with crystallized 
carbonate of Lime ; the shell and ferriferous lining being 
very liable to decay, have generally disappeared, and 
left the remainder of the cast in detached portions. The 
most perfect specimen of this kind, is one in the pos- 
session of our valuable and scientific Friend, James 
Vol. Y. August, 1823. 
