73 
AMMONITES teviusculus. 
TAB. CCCCLI.-^s. 1 and 2. 
Spec. Char. Discoid, carinated, umbilicated, 
obscurely radiated; carina distinct; radii 
waved, alternately long and short, slightly 
elevated ; umbilicus small, exposing parts of 
the inner whorls ; aperture sagittate. 
One half of the diameter of the shell is occupied by the 
aperture, a third of the other half by the umbilicus, in 
full grown individuals ; in young ones the umbilicus is 
larger. The front is obtuse with a large prominent keel 
in the middle of it; the sides are rather convex marked 
with waved, elevated radii, that are broader and less 
conspicuous on the outer whorls of the full grown shells. 
In young shells the aperture is oblong, rather square ; as 
the shell grows older, the aperture becomes longer, more 
deeply notched by the preceding whorl, and narrower 
towards the front. 
Found in the inferior or Ironshot Oolite, at Dundry 
by G. W. Braikenridge, Esq. to whose liberality we are 
indebted for a series of specimens. 
