113 
AMMONITES Koenigi. 
TAB. CCLXIII, Figs. ], 2, and 3. 
3p. Char. Discoid,, convex, with radiating undu- 
lations ; inner whorles half exposed ; mar- 
ginal undulations numerous ; central undu- 
lations few., very prominent ; aperture cor- 
date elongated. 
The young state of this Ammonite is less depressed* 
so that the aperture is then nearly orbicular; when full 
grown the last whorl e occupies two-fifths of the diame- 
ter ; the margin is rounded ; the undulations upon it ex- 
tend also half way over the sides* and every third or 
fourth is met by a large undulation that rises almost into 
a low tubercle ; the septa are few, their lobes are not 
deeply sinuated ; whorles about six. 
The young shells represented at figs. 1 and 2 are from 
Kelloways, which place also furnishes full sized speci- 
mens, with a dull sparry Carbonate of Lime in place of 
the shell. Fig. 3 is from Charmouth ; it is in a nodule 
of indurated Marie; the shell is mostly reduced to a 
chalky texture, but is in some parts pearly. This was 
presented to me some years ago by Dr. W. E. Leach, of 
the British Museum. I name it Koenigi after his col- 
league, who is now so busily investigating fossil remains. 
