154 
AMMONITES curvatus. 
TAB. DLXXIX— ^g. 2. 
Spec. Char. Discoid, subumbilicate, radiated ; in- 
ner whorls almost concealed ; radii falcate, 
near equal over half the whorl, then bent, and 
alternately broad and narrow ; the broad ones 
furnished with two tubercles each near the 
front, the narrow ones gradually lost towards 
the front; front flat, narrow ; umbilicus large, 
with a row of flattened tubercles around it ; 
aperture obtusely sagittate. 
Syn. A. curvatus. Mantell Geol. Suss . p. 118. 
tab. 21. /. 18. 
C6 rp 
1 his Ammonite is nearly allied to the preceding, but 
is evidently a distinct species. In A. falcatus the cur- 
vatures are more numerous than the oblique radii ; but 
in the present species the proportions are reversed, two 
or three radii uniting to form one curved rib. The ter- 
minations of the ribs in the latter are tubercular, and 
separated from each other by a sulcus ; in the former 
they are gently curved, and appear as if folded or plaited 
over each other. The umbilicus is rather deeper than 
in A. falcatus, and has a marginal row of oblique tuber- 
cular projections, from each of which two or three radii 
proceed. 
“ Locality, Hamsey.” 
We are favoured with this along with the last: it ap- 
pears to be unique. In both descriptions parts of Mr. 
Mantell’s are copied, as they appeared so appropriate. 
The furrow in the front mentioned by him is the situa- 
tion of the siphuncle, and of course would be covered by 
the shell. 
