23 
AMMONITES SowerbiL 
TAB. CCXIIL 
Syn. A. SowerbiL Miller MSS. Catalogues . 
Spec. Char. Discoid,, carinated, with about eight 
spiniform tubercles upon each whorl ; keel de- 
fined, entire ; aperture elliptical. 
Yar. iS aperture circular, keel sometimes impressed. 
"V glut ions about four, the inner ones concealed to the 
bases of the tubercles ; the outer part of the volutions 
has many gentle undulations ; the inner part is even*, 
except that the base of each tubercle is extended towards 
the centre in an obtuse ridge. The keel nearly sepa- 
rated from the body of the shell ; it is round and entire. 
In xar. |3 the ridges from the bases of the tubercles are 
more prominent^ and the keel sometimes so far sunk as 
to have a furrow on each side of it. The" inner whorls of 
var. a appear to he more gibbose than the outer ones. 
Mr. Miller considers the shell figured as one of his 
rarest specimens : his collection has also to boast of seve- 
ral smaller specimens,, belonging to var. which vary 
in the gibbosity of the whorls; they were all found at 
Dundry, in the Inferior Oolite. 
