PLATE XXIII. 



PA8E 



Fig. 15. AMMONITES FRATERNUS. 137 



15 a. Cross 8 ection of last yolution. 



15 b. Septum. 



Fig. 16. A. STOLICZKANUS. 135 



16 a. Front view of the same. 



I 



Fig. 17. ' Septum of ANCYLOCERAS RMONDII. 138 



Fig. 18. ? ANCYLOCERAS LINEATUS. Side view of straight limb. 139 



18 a. Dorsal view of same. 



18 b. Cross section of same. 



18 c. Septum. 



